Added support for AJAX GET requests to log in and sign up

When a request comes in for the login or signup views, we will detect an AJAX
request and serve a different template.
Added complete sign up AJAX template support
Bumped version
Added ConfirmEmailView.after_confirmation

This new method allows site developers to override the behavior after a user
has confirmed their email address. By default, it will mark the User object
active.
Bumped version
Added SignupView.create_email_address

This commits moves the logic for creating the EmailAddress object to its own
method. Site developers can now override the behavior of the creation of this
object without having to redefine SignupView.form_valid.
Bumped version
Fixed email confirmation logic

This commit prevents the User object from being marked inactive in cases where
an email address is verified by some other means than email confirmation.
Bumped version for next release
Changed variable name to be descriptive and not stomp on builtin
Changed default_redirect session behavior

Destroy the session variable after grabbing it from the session. This prevents
leaking the data to other requests.
Cleaned up fallback URL behavior
Bumped version
Update usage docs to clear up confusion about customizing signup

There was some confusion with regards to the the custom
signup view example in that it was called `create_profile`
but it was clearly updating a profile that had already
been created.
Fix a typo left by a previous document update
Updated dependencies to latest versions
Bumped version for next release