webadmin: System tree refresh

- Automatically refresh the system tree when a new event comes in
  or the user does an action.
- Fixed issue where the tree would collapse when refreshing.
- Fixed issue where the selection of the tree would disappear when
  refreshing.

Change-Id: I062163b1f6d2e5fcfd1539b69a3d0d2cee674654
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=987953
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1057081
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1072505
Signed-off-by: Alexander Wels <awels@redhat.com>