webadmin: Bad vertical alignment in add user screen

When adding a new user, the dropdown box for
selecting the domain and the search box are misaligned

Change-Id: I967023959027f2b977592cf8a6b61952960e24c3
Bug-Url: https://bugzilla.redhat.com/1057109
Signed-off-by: Ravi Nori <rnori@redhat.com>