webadmin, userportal: stop special handling of '@' in user name

Simplify login page behavior: send user-name as is (don't parse by '@', etc.),
don't disable the Domain drop-down.

Change-Id: If7568c98c34e6edbd011949c5bad397aeba7b4ae
Bug-Url: https://bugzilla.redhat.com/1112252
Signed-off-by: Greg Sheremeta <gshereme@redhat.com>