tastypie API tweak. Fixes #156

[dchud]

Okay, cool, this definitely works. On master:

dchud@dchud-mba2:~$ curl -X GET "http://gwdev-dchud12.wrlc.org:8082/api/v1/bag/?path__contains=gw_chrs" | jq '.'
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    69    0    69    0     0    979      0 --:--:-- --:--:-- --:--:--  1169
{
  "error": "'contains' is not an allowed filter on the 'path' field."
}

On this branch:

dchud@dchud-mba2:~$ curl -X GET "http://gwdev-dchud12.wrlc.org:8082/api/v1/bag/?path__contains=gw_chrs&limit=1" | jq '.'
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   975    0   975    0     0   7861      0 --:--:-- --:--:-- --:--:--  8783
{
  "objects": [
    {
      "stats": "{u'total_size': 42136013, u'total_count': 4, u'types': {u'xml': {u'count': 1, u'size': 2104}, u'doc': {u'count': 1, u'size': 16172}, u'tif': {u'count': 1, u'size': 42079526}, u'pdf': {u'count': 1, u'size': 38211}}}",
      "bag_type": "",
      "bagname": "chrs_minutes_8_10_04_bd_mtg_draft_of_8_22_04",
      "created": "2013-07-31T08:23:39.802855",
      "item": "/api/v1/item/38989/c01wf73xc49j/",
      "machine": "/api/v1/machine/2/",
      "path": "gw_chrs/chrs_minutes_8_10_04_bd_mtg_draft_of_8_22_04",
      "payload": [
        [
          "data/gw_chrs_minutes_8_10_04_bd_mtg_draft_of_8_22_04.doc",
          "16172"
        ],
        [
          "data/gw_chrs_minutes_8_10_04_bd_mtg_draft_of_8_22_04.tif",
          "42079526"
        ],
        [
          "data/gw_chrs_minutes_8_10_04_bd_mtg_draft_of_8_22_04.pdf",
          "38211"
        ],
        [
          "data/dublin_core.xml",
          "2104"
        ]
      ],
      "resource_uri": "/api/v1/bag/chrs_minutes_8_10_04_bd_mtg_draft_of_8_22_04/"
    }
  ],
  "meta": {
    "total_count": 14,
    "previous": null,
    "offset": 0,
    "next": "/api/v1/bag/?limit=1&path__contains=gw_chrs&offset=1",
    "limit": 1
  }
}

Definitely better. :)