Add view decorator for user update views, add URL tests for user update.

Checks the username, returns 404 if the username doesn't exist, 403 if it's
for the wrong user, and replaces username with the user otherwise.
Add endpoint for updating user profile photos
Add API endpoint which calls upload_user_photo
Fix indentation and remove vim filetype comment
Add photo upload to user profile page
Merge pull request #835 from maurizi/topic/447/userProfilePhoto

User profile photo upload