webadmin: cluster policy in cluster views

- select cluster policy in new/edit cluster dialog.
- allow to add custom properties for cluster policy.
- remove old view.
- hiding policy subtab for now, till new desing is introduced.

Change-Id: Id27916bf545eacbcb7ae7658bd89ddc1c6251dfa
Signed-off-by: Gilad Chaplik <gchaplik@redhat.com>