webadmin: Implement permission sorting by role icon

Implemented sorting for permission subtabs according to the role icon
(ordinary user is lesser than administrator).

Change-Id: I3a2c97315bda060e44b662562e1e08652881d72f
Bug-Url: https://bugzilla.redhat.com/1120054
Signed-off-by: Lior Vernia <lvernia@redhat.com>