enable user to delete own user profile, and only allow a user to delete one's own profile

[mitchdowney]

I was considering adding the UserProfileDeleteView after I figured out how to fix #45, but I decided not to yet because I am not sure if deleting userprofiles will screw up foreignkey relationships? Supposedly disabling Django's "is_active" feature is preferred over actually deleting userprofiles.

When a user delete's his userprofile, all comments left by the user should be removed and all of the user's candidate profiles should be removed.