webadmin:  In Add Users and Groups dialog the namespace drop down is not aligned

The namespace selection drop down in
add users and groups dialog is not aligned

Change-Id: I9bd2f5465a047dc4616e4fa0e7f9dea2f64f9bcc
Bug-Url: https://bugzilla.redhat.com/1128234
Signed-off-by: Ravi Nori <rnori@redhat.com>