serializer update (handle None), wrap validation errors
Merge pull request #7 from nvillalva/serializing-and-validating

serializer update (handle None), wrap validation errors
handle unknown exceptions
Dependencies for development updates

* make manage.py executable
* add mock and South to `requirements.txt` and setup.py's `test_requires`
* add south to `INSTALLED_APPS` in `tests/settings.py`
fix setup.py typo
fix ordering of simplejson import attempt
remove unusued imports
Merge pull request #9 from nvillalva/serializing-and-validating

More Exception updates
Merge pull request #8 from mapmyfitness/master

serializer update (handle None), wrap validation errors