Fixes for the video tests

Tests now pass and they don't call url_exists() which does a network
request.  We also now test what happens if url_exists() returns False.
Made kaltura syncing tests pass
Fixed some unittests.

Removed the teams tests for the add videos view.  One was failing and
we have tests for the form itself in videos.tests.forms.  I think
those are good enough.
Switched to factoryboy for unittests (#742)

Factoryboy is awesome.

The new code works basically the same as the old code, the one gotcha
is factories.VideoFactory doesn't set primary_audio_language_code like
test_factories.create_video() used to.  I think this is better since
in the real-world, videos get created with
primary_audio_language_code=NULL.  However, there could be issues if
the calling code expects the old behavior.
Deleting test_factories
Merge pull request #1444 from pculture/gh-742

Gh 742
Merge remote-tracking branch 'origin/staging' into brightcove

Conflicts:
	apps/videos/tests/forms.py
Couple of small fixes for importing videos

Created ImportedVideo objects in reverse order from the feed.  This
way if you sort the rows by descending id, the latest videos are on
top.
Better method of detecting new items in a feed (#1445)

Before, we would remember the top link in our RSS feed, and when we
parsed it again we would stop when we saw it.  This fails pretty bad
for brightcove feeds, since they are ordered oldest-first.

Instead, just try to import all videos, but skip ones that have
already been created.

This also alters the youtube next link code handling a bit.  Now,
instead of only checking the next link on the first pass (when we
don't have last_link set), we check the next link as long as all of
the items in the feed are new.