The @requires_user_profile decorator only worked with unbound methods

on Python 2.x, but the concept of an unbound method is very different on

Python 3.x. Instead of being a MethodType, it's just a standard

function, meaning we can't check im_func/__func__, but rather we

need to check the function itself.
This change updates the decorator to perform the appropriate checks on

both Python 2.x and 3.x.

Unit tests using this decorator pass on Python 2.7, 3.4, 3.5, and 3.6.