Remove downcasing of diaspora_handle, verify that diaspora_handle querying and validation is case insensitive.

username can be any case, but diaspora handle should always, always, ALWAYS be lowercase, for webfinger reasons

removed loop and hidden checkboxes from publisher.  hidden field passes single aspect id or :all to controller

Tested with Firefox, Chrome and Mobile Safari (IE8 is broken anyway)

RegistrationsController#create deals with validation errors. Username, email, password now required on sign-up.

Remove RegistrationsController#new (which just called super, so it's not necessary).