Mobile API release

@andy-armstrong: Need to check tests. Please don't stage yet.
@jimabramson, @gwprice: as a heads up, I needed to add this because I'm bumping the version of djangorestframework from 2.3.5 -> 2.3.14, and apparently this is no longer output by default in the HyperlinkedModelSerializer (I got a slew of errors about "missing field 'url'" in tests).