Add documentation for new infinite_invites command
Style cleanup
Relocate signal receiver code to its own module
Remove pointer to blog post

The blog post pretty much is duplicating much of
old docs. Since docs are available and are kept
up to date, the blog post is more and more
irrelevant.
Translate templates
Replace remaining_invites template tag

Replaced in favor of a simple inclusion tag called
invites_remaining that will ship with a sane default
template.
Update view to use different imports/decorators

1. We can generally expect the json module to be
   available now, so no need to use what ships with
   django
2. require_POST is just simpler and more direct
3. Using login_required is clearer as well instead
   of using custom logic.
Rewrite view to support bootstrap-ajax

A secondary benefit to this is the separation of
concerns between the form and the view. The
validation logic was relocated to live in the form.

As a result the form now requires a user object
upon instantiation.
Update docs per 1.0 changes
1.0