rhbz1065806 - Fix stuck loading image when changing version statistics type.

With 4.x changes to Richfaces, the behaviour of the a4j:status component changed and was causing problems by not hiding the "loading" status indicator. Refactored the page to use the updated way of using the status component.
Merge pull request #380 from zanata/rhbz1065806

rhbz1065806 - Fix stuck loading image when changing version statistics type.