New workout page and forms

## New pages:
http://127.0.0.1:8000/workout/
 * GET - lists out existing workouts
 * POST - creates new workout
http://127.0.0.1:8000/workout_detail/1/
 * GET - lists out all the workoutsets for this workout
 * POST - create new workoutsets

I am not really happy with the way the views are structured, but I wanted to get a baseline (even if it was hacky) so we could see what the user scenario was starting to look like.

These pages are restricted to logged in users https://docs.djangoproject.com/en/1.6/topics/auth/default/ and you will only see your workouts.

## New Admin Pages
http://127.0.0.1:8000/admin/mainapp/
* Notice we modified the classes in model to override __str__, which changes how they display.
* Tips on how to expand functionality - https://docs.djangoproject.com/en/1.6/intro/tutorial02/