Update DRF to 2.3.14.

The reason I want o do this is primarily because of the line in the 2.3.13 release notes "Fix `default` argument when used with serializer relation fields.". I'm running into this problem in my buddyup APIs. The full change log is here: http://www.django-rest-framework.org/topics/release-notes.

Other reasons include generally keeping up with versions, two security fixes (which shouldn't affect us) and liking larger numbers.

Note that this doesn't update to the absolute latest version, 2.4.3, but instead updates to the latest 2.3.x release. This is because 2.4.x requires South 1.0 because 2.4.0 also adds support for Django 1.7's built in migrations, which South 1.0 is also compatible with. We don't need this yet, but we should eventually upgrade to both South 1.0 and DRF 2.4.x.

r?