Feature: Add an API to force OVF_STORE update
Reason: The need to control the timing of an ovf_store volume update, rather than wait for the scheduled job for this, and help recuperate from a previous update that is presumably defective.
1. New REST API action - updateovfstore .
2. New context menu option - Update OVFs, when right clicking over an active storage domain.
A new button WAS NOT supplied since this should not be a common operation.