CP-5095:Retrieve a list of SRs required to recover a VM through xapi

Signed-off-by: Akshay Ramani <akshay.ramani@citrix.com>
Fix issue of local SR
Change API call to 'get_SRs_required_for_recovery'
Api call for VM Appliance
Filter by required_SR_list
Remove try..with block that was not required
Fix release_version of get_SRs_required_for_recovery

Signed-off-by: Jon Ludlam <jonathan.ludlam@citrix.com>
Merge pull request #1869 from jonludlam/creedence-cp-5095

CP-5095:Retrieve a list of SRs required to recover a VM through xapi