Use django rest framework 3.0 pre-release

See https://github.com/tomchristie/django-rest-framework/blob/version-3.0/docs/topics/3.0-announcement

Bear in mind for [#78037278]
Remove `method_name` from `SerializerMethodField`

See https://github.com/tomchristie/django-rest-framework/blob/version-3.0/docs/topics/3.0-announcement.md#optional-argument-to-serializermethodfield
Use `.query_params` rather than `.QUERY_PARAMS`

See
https://github.com/tomchristie/django-rest-framework/blob/version-3.0/docs/topics/3.0-announcement.md#the-data-and-query_params-properties
Replace `lookup_field` with `extra_kwargs`

In `HyperlinkedModelSerializer` for location.

See https://github.com/tomchristie/django-rest-framework/blob/version-3.0/docs/topics/3.0-announcement.md#changes-to-hyperlinkedmodelserializer
Point requirements.txt at a specific commit.
Merge pull request #104 from sealevelresearch/django-rest-framework-3

Use django rest framework 3.0 (pre-release)