userportal,webadmin: synchronize grid refresh

- Updated code to have refresh rates across tabs and sub
  tabs be identical. So if you switch the refresh rate on
  lets say the VM tab, the same refresh rate is used for
  all other tabs. As well as affecting the refresh rate of
  the events/alerts and tasks list.
- Fixed duplicate timers being created for EventListModels
  and its sub classes.
- Fixed each GridTimer having its own EventBus, which then
  didn't actually communicate with the rest of the system.
  Now all the GridTimers have the correct EventBus.

Change-Id: I8742785cb9b3d890c39859586b03cd53c64b31e5
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=879662
Signed-off-by: Alexander Wels <awels@redhat.com>