delete Spot json cache on SpotImage delete; fix SPOT-1028
Merge branch 'absent_craig' of github.com:uw-it-aca/spotseeker_server into absent_craig
Merge branch 'master' into absent_craig
It's actually the cached json at the image's spot's pk we want to delete in the case that an image is deleted, not the cache at the SpotImage's pk.
Using django.test.TestCase gets these to actually be recognized by the test harness (and run!)
Initial implementation of display_index ordering for SpotImages. The included datamigration does set an initial display_index for each SpotImage a Spot has, but it's currently possible to have a SpotImage without a display_index. There's also an unrelated failing unit test here, which I want to fix in a separate commit.
Fixed unit test that was trying to compare creation_date and modification_date that will NOT be exactly the same, but should be close.
Handled giving a display_index to images that are POSTed without one.