webadmin: user main tab sorting

- Implemented sorting on Users main tab
  - No sorting on email.
- Implemented sorting on Users sub tabs.

Change-Id: I87781ecd94ad15fb7db9209c347a57e3bd59db46
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1119873
Signed-off-by: Alexander Wels <awels@redhat.com>