Feature highlight searched text

[nonumpa]

Figma

1. Add highlight support for ListArticles and ListReplies
2. Fix ListReplies reference search(more_like_this) Although the document says we can directly use "fields" : ["title", "description"] to match multiple field, the results aren't correct.

Fixes #51

Problem (solved by version 2)

Version 1: Get hyperlinks highlight in edges.node.

hyperlinks breaks into (highlight.)hyperlinks.title array, (highlight.)hyperlinks.summary array, etc. It's difficult to know which hyperlink group the highlight belongs to.

There's an issue discussion about highlight array field.

Sample: Search a article that contains seven hyperlinks and two of them are invalid(can't fetch). Elasticsearch Response: (I didn't highlight summary in this query)

"highlight":{
               "text":[
                  "親愛的朋友，\n\n您好！現在，全世界有成千上萬<HIGHLIGHT>蜜蜂</HIGHLIGHT>逐漸死去，但兩天後，歐盟有望全面禁用危及<HIGHLIGHT>蜜蜂存續的有毒農藥</HIGHLIGHT>！\n\n頂尖的科學家以及農民聯盟都不斷呼籲實施<HIGHLIGHT>禁令</HIGHLIGHT>，歐盟國家的民眾也普遍支持；英、法、德等12國將投下支持票，但我們還需要另外4個國家的一票才能贏得星期五的<HIGHLIGHT>表決</HIGHLIGHT>。一旦歐盟通過<HIGHLIGHT>禁令</HIGHLIGHT>，我們就有機會進而推動更多國家跟進。\n\n目前<HIGHLIGHT>表決</HIGHLIGHT>的情勢尚未完全明朗，所以每一個連署簽名都至關重要 -- 邀請"
               ],
               "hyperlinks.title":[
                  "<HIGHLIGHT>拯救蜜蜂</HIGHLIGHT>：<HIGHLIGHT>農藥禁令表決倒數中</HIGHLIGHT>",
                  "<HIGHLIGHT>拯救蜜蜂</HIGHLIGHT>：<HIGHLIGHT>農藥禁令表決倒數中</HIGHLIGHT>",
                  "<HIGHLIGHT>拯救蜜蜂</HIGHLIGHT>：<HIGHLIGHT>農藥禁令表決倒數中</HIGHLIGHT>",
                  "歐盟拼<HIGHLIGHT>農藥</HIGHLIGHT>減半不減產，禁用類尼古丁<HIGHLIGHT>救蜜蜂</HIGHLIGHT>，百萬連署反嘉磷塞 | 上下游News&Market",
                  "歐盟最新草案 類尼古丁<HIGHLIGHT>農藥嚴重危害蜜蜂</HIGHLIGHT> 預計全面禁用 | 上下游News&Market"
               ]
            }

Version 2: Get hyperlinks highlight through inner_hit (in nested query of hyperlinks).

This can get groups of hyperlink highlight when the more_like_this hyperlinks query matched. But the problem is we can't highlight hyperlinks if the query only matches the text field.

Finally we choose version 2, because we want to show the hyperlinks matched only.

Sample: Search a article that contains seven hyperlinks and two of them are invalid(can't fetch). Elasticsearch Response:

{
   "hyperlinks":{
      "hits":{
         "total":3,
         "max_score":91.32045,
         "hits":[
            {
               "_index":"articles_v1_0_2",
               "_type":"doc",
               "_id":"1i95bq4c279wv",
               "_nested":{
                  "field":"hyperlinks",
                  "offset":2
               },
               "_score":91.32045,
               "_source":{
                  "summary":"拯救蜜蜂：表決倒數計時中 致  各歐盟成員國、世界各國領袖及農業部長：:\n                \n                我們籲請您們即刻禁用類尼古丁（neonicotinoid）農藥。蜜蜂族群的衰亡將會使我們的整個食物鏈面臨崩壞，如果您迅速採取行動，我們就有望拯救蜜蜂免於滅絕。2,066,744 已簽名。讓我們達到 5,500,000更新: 27 四月 2018好消息，我們贏了!! 經過我們的史上規模最大的守護蜜蜂連署，以及對各國部長發送的數千封訊息；歐盟通過這項農藥禁令了！這是個重大進展，為更為永續的農業開啟了新時代。但我們仍須凝聚力量持續施壓 -- 接下來，這場戰役將在美國、加拿大以及世界其餘國家登場。請持續分享並邀請更多人加入連署！發佈日期： 25 四月 2018致  各歐盟成員國、世界各國領袖及農業部長：:...",
                  "title":"拯救蜜蜂：農藥禁令表決倒數中",
                  "url":"https://secure.avaaz.org/campaign/ct/save_the_bees_neonics_loc_ns/?tUlKRlb&v=500463352&cl=14353930467&_checksum=767b05c6ceeaaced891d5ac06558c6c787260449170dbc0659039ba024e81252"
               },
               "highlight":{
                  "hyperlinks.url":[
                     "https://secure.avaaz.org/campaign/ct/save_the_bees_neonics_loc_ns/?tUlKRlb&v=500463352&cl=14353930467&_checksum=767b05c6ceeaaced891d5ac06558c6c787260449170dbc0659039ba024e81252"
                  ],
                  "hyperlinks.title":[
                     "<HIGHLIGHT>拯救蜜蜂</HIGHLIGHT>：<HIGHLIGHT>農藥禁令表決倒數中</HIGHLIGHT>"
                  ],
                  "hyperlinks.summary":[
                     "<HIGHLIGHT>拯救蜜蜂</HIGHLIGHT>：<HIGHLIGHT>表決倒數</HIGHLIGHT>"
                  ]
               }
            },
            {
               "_index":"articles_v1_0_2",
               "_type":"doc",
               "_id":"1i95bq4c279wv",
               "_nested":{
                  "field":"hyperlinks",
                  "offset":1
               },
               "_score":91.32045,
               "_source":{
                  "summary":"拯救蜜蜂：表決倒數計時中 ...",
                  "title":"拯救蜜蜂：農藥禁令表決倒數中",
                  "url":"https://secure.avaaz.org/campaign/ct/save_the_bees_neonics_loc_ns/?tUlKRlb&v=500463352&cl=14353930467&_checksum=767b05c6ceeaaced891d5ac06558c6c787260449170dbc0659039ba024e81252"
               },
               "highlight":{
                  "hyperlinks.url":[
                     "https://secure.avaaz.org/campaign/ct/save_the_bees_neonics_loc_ns/?tUlKRlb&v=500463352&cl=14353930467&_checksum=767b05c6ceeaaced891d5ac06558c6c787260449170dbc0659039ba024e81252"
                  ],
                  "hyperlinks.title":[
                     "<HIGHLIGHT>拯救蜜蜂</HIGHLIGHT>：<HIGHLIGHT>農藥禁令表決倒數中</HIGHLIGHT>"
                  ],
                  "hyperlinks.summary":[
                     "<HIGHLIGHT>拯救蜜蜂</HIGHLIGHT>：<HIGHLIGHT>表決倒數</HIGHLIGHT>"
                  ]
               }
            },
            {
               "_index":"articles_v1_0_2",
               "_type":"doc",
               "_id":"1i95bq4c279wv",
               "_nested":{
                  "field":"hyperlinks",
                  "offset":0
               },
               "_score":91.32045,
               "_source":{
                  "summary":"拯救蜜蜂：表決倒數計時中...",
                  "title":"拯救蜜蜂：農藥禁令表決倒數中",
                  "url":"https://secure.avaaz.org/campaign/ct/save_the_bees_neonics_loc_ns/?tUlKRlb&v=500463352&cl=14353930467&_checksum=767b05c6ceeaaced891d5ac06558c6c787260449170dbc0659039ba024e81252"
               },
               "highlight":{
                  "hyperlinks.url":[
                     "https://secure.avaaz.org/campaign/ct/save_the_bees_neonics_loc_ns/?tUlKRlb&v=500463352&cl=14353930467&_checksum=767b05c6ceeaaced891d5ac06558c6c787260449170dbc0659039ba024e81252"
                  ],
                  "hyperlinks.title":[
                     "<HIGHLIGHT>拯救蜜蜂</HIGHLIGHT>：<HIGHLIGHT>農藥禁令表決倒數中</HIGHLIGHT>"
                  ],
                  "hyperlinks.summary":[
                     "<HIGHLIGHT>拯救蜜蜂</HIGHLIGHT>：<HIGHLIGHT>表決倒數</HIGHLIGHT>"
                  ]
               }
            }
         ]
      }
   }
}

[coveralls]

Coverage increased (+0.08%) to 88.666% when pulling ba79882b6bbee4bd524577f332515fc60d0a9681 on features/51-highlight into a9a68b9d1d5a3b75a32b021c8b799dd58c1fb01c on master.