Add test to show friends can't view children's profiles

I'll fix this shortly.
Ensure you can't unregister other users' children

Also, allow viewing friends' children's profiles.
Remove the "Unregister child" link if you're viewing a profile as a friend
Always pass the request object into our mail-sending function

This will allow us to get to the domain in a follow-up
change.
Ensure invitations include the full server path

Also, infrastructure to make doing this easier for future
emails.
Add notes about speed improvements of a couple of test settings
Email notification on friend request

Also, consolidate all the FakeRequest() stuff in tests to a
fixture.
Remove unused variable, and correct test name to reflect reality
This is now done
Add tests for friend request email notifications
Ensure we set the confirmation time of friend requests
Re-order URLs
Moving user-specific URLs to their own place
Be consistent with the URL variable for users
Hopefully more obvious URLs
Fixing bad URLs for templates post the URL move

Note to self: I don't have 100% template coverage.