Drf-generators

Minor fixes
- Only include depth in serializers when >0, "modelviewset" in format list - jeverling
- Removed blank lines from start/end of files and unused imports - jeverling

Features
- option (`-d`, `--depth`) added to set serialization depth

Options were not being parsed correctly in versions of Python < 3.4. Fixed to user optparse.

There were a couple bugs to iron out with the way django treats argparse in 1.7 and 1.8. Now compatible with both versions.

Features
- ModelViewSet generation

Bugfixes/Enhancements
- CI set up on Travis
- Testing refactored to one app

Features
- function based views are now supported
- `--force` option added to overwrite files
- added test api for function based views
- `--format` option added for view format. `viewset` by default

Style Changes
- moved templates to separate files for each view style

Bugfixes
- fixed `input` and `raw_input` for python 2 and python 3