Added better schemas for image members, revised tests.

Related to bp glance-api-v2-image-sharing

Change-Id: I01c7fdb78177aaee97f6e7836dea3326b57be33c
Test date with UTC instead of local timezone.

iso_format test uses local timezone so it can fail at certain times
of the day depending on which timezone the tests are run in.

Fixes bug 1139131

Change-Id: I8fe423d96c438b46a9307fe1ecf648707183ff1c
Update db layer to expose multiple image locations

* The DB API now exposes a 'locations' image attribute rather than
  'location'. The new field is guaranteed to be a list of zero of
  more items
* The v1 and v2 APIs only look for the first item in the list of
  locations.
* Related to bp multiple-image-locations

Change-Id: I830b383d8a8e50a01e461658fb9abe384de1a353
Merge "Added better schemas for image members, revised tests."
Merge "Test date with UTC instead of local timezone."