Add NFT properties

[modersohn]

• similar but not necessarily identical to traits
• each displayed in an expandable section

[fudgebucket27]

Great idea. Looks fine to me. Merging into dev

[modersohn]

This is now causing problems with - IMO - malformed JSON, e.g. for 0x32f006a901505c8c015714cc4390f7f5447c1b07983b050c9cd92da90777584c.

The JSON looks like this:

{
   "image":"ipfs://QmTfNgyzsH6KhbFbawhNks1Xwm1pkh6ofMiXTfFYrupCXL",
   "name":"Welcome to L2",
   "royalty_percentage":10,
   "description":"Gifted with 💙 by @ThisBeTom via https://github.com/tomfuertes/free-loopring-nft",
   "properties":[
      {
         "key":"PowerTo",
         "value":"ThePlayers"
      },
      {
         "key":"Love",
         "value":"Everyone"
      },
      {
         "key":"AndTell",
         "value":"TheTruth"
      }
   ]
}

The problem is, that causes the whole deserialisation to fail, so it doesn't show any of the meta data.