webadmin: load image refreshing data

- Fixed when switching main tabs always show 'loading' image
so the user has feedback something is happening.
- Fixed when switching to sub tab with grid always show
loading image so the user has feedback something is happening.
- Added code to give user feedback when manually refreshing grid
using the refresh button.
- Automatic refresh unchanged to simulate 'push' technology while
we are still doing a data pull.

Change-Id: I8be80df57eafc4244c57029f8260d4d67c47b3f4
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=907491
Signed-off-by: Alexander Wels <awels@redhat.com>