webadmin: Event tab sorting

- Implemented sorting for Events main tab
  - Not implemented for event id, cluster.

Change-Id: I027d5cd5aa83610384659b873703787a7472f713
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1119873
Signed-off-by: Alexander Wels <awels@redhat.com>