Fixes 3PAR snapshot failure with optional params
Fixes 3PAR snapshot failure with optional params

Create snapshot fails when HP3PAR hp3par_snapshot_retention and/or
hp3par_snapshot_expiration parameters were set in cinder.conf. The
params were being sent to the backend as strings instead on integers.

Change-Id: I24d0bc133c48b47a27f5c112e9cd924dd0fa3bcc
Closes-bug: #1461640

tlakshman26/cinder-https-changes,nikesh-mahalka/cinder,Paul-Ezell/cinder-1,openstack/cinder,openstack/cinder,JioCloud/cinder,Nexenta/cinder,sasukeh/cinder,phenoxim/cinder,mahak/cinder,apporc/cinder,Hybrid-Cloud/cinder,tlakshman26/cinder-https-changes,tlakshman26/cinder-new-branch,nexusriot/cinder,CloudServer/cinder,cloudbase/cinder,takeshineshiro/cinder,leilihh/cinder,manojhirway/ExistingImagesOnNFS,scality/cinder,potsmaster/cinder,j-griffith/cinder,manojhirway/ExistingImagesOnNFS,ge0rgi/cinder,Datera/cinder,leilihh/cinder,scottdangelo/RemoveVolumeMangerLocks,saeki-masaki/cinder,bswartz/cinder,NetApp/cinder,takeshineshiro/cinder,tlakshman26/cinder-new-branch,nikesh-mahalka/cinder,duhzecca/cinder,NetApp/cinder,nexusriot/cinder,bswartz/cinder,JioCloud/cinder,Paul-Ezell/cinder-1,sasukeh/cinder,eharney/cinder,apporc/cinder,phenoxim/cinder,dims/cinder,tlakshman26/cinder-bug-fix-volume-conversion-full,Hybrid-Cloud/cinder,tlakshman26/cinder-bug-fix-volume-conversion-full,j-griffith/cinder,eharney/cinder,petrutlucian94/cinder,Nexenta/cinder,mahak/cinder,winndows/cinder,winndows/cinder,Datera/cinder,dims/cinder,CloudServer/cinder,petrutlucian94/cinder,scottdangelo/RemoveVolumeMangerLocks,saeki-masaki/cinder,scality/cinder,cloudbase/cinder,potsmaster/cinder,duhzecca/cinder