webadmin: auto select dialog tab

- Automatically select the first dialog tab with
  an error in it when clicking ok on the dialog.
- Centralized logic that marks invalid tabs as invalid.
- Fixed some of the high light logic in the following popups:
  - VMs
  - Hosts
  - Clusters

Change-Id: I2e9c5ad0cd3ee7f54606958b1fc8abd2bbd972ed
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1057386
Signed-off-by: Alexander Wels <awels@redhat.com>