Testing for django-localflavor-us

@adrianholovaty This is my first attempt at making test run with the rest of the app. I moved the tests into the `django-localflavor-us` and added a test_settings.py to the test directory. 

That being said I am will to iterate to make the better in and get this done. 

I have included documentation on how to test it in the readme. 

If we need to get a matrix up and running for older versions of `django` and `python` I can also look into this if the layout is acceptable.