Add decorator to throttle requests.

https://github.com/madewithbytes/us_ignite/issues/119

Decorator that throttles the specified methods ``POST`` and ``GET``
by default, uses the authenticated user ID or the headers:
``X_FORWARDED_FOR`` or  ``HTTP_X_FORWARDED_FOR`` or ``REMOTE_ADDR``.

Usage:

- Throotle with the ``POST`` method by 30 seconds

    @throttle_view(methods=['POST'], duration=30, prefix='FOO')

- Throotle with the default values

   @throotle_view()
Add profile method to display a user friendly email.

The email is displayed in the format ``NAME <EMAIL>``,
useful when contacting the users.
Add contact user section.

https://github.com/madewithbytes/us_ignite/issues/118

Registered users can contact other users by using the contact
form. The contact form sends the user details to the
destinatary using the ``Reply-To`` header to show the
details of the original sender.

This conceals the identity of the recipient unless they
explicitly decide to contact them.