Utilize select_related() for user & user profiles. This commit also removes the caching of the avatar URL in the avatar template tag. This is because we are now using select_related, so we already have the profile & avatar when we get to the tag. Thus we don't need to waste time querying the cache. Removed an apparently unused member map template as well.

"""The wiki application integrates an external Wiki app with our Django
application.

The wiki application has no models. It consists of some signals and
middleware only.

"""
import wiki.signals