webadmin: version in feedback url.

- Added the ability to specify the version of ovirt in the
  feedback url.
- Added version retrieval to get the configuration from the
  cache.
- Renamed getRpmVersionFromPublic to be non public.

Change-Id: Ib7f4305ff1e3bd30aa13f1ba381186cf9e910c71
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=968511
Signed-off-by: Alexander Wels <awels@redhat.com>