Prevent issues with name length on registration

Truncate the first/last name fields when syncing from couchdb to
Django and prevent the reverse sync clearing the correct versin of a
persons name.
Use couch instead of Django for a users name

Switch to using the (non truncated) version of a users name from the
couchdb store instead of the Django copy.
Refactor user's name string in header
Add translation blocks for registration confirmation pages
Add translation block in registration success
Add tests for user sync changes
Merge pull request #965 from dimagi/name-length-error

Name length error