Add mock for cinder-rtstool call in tests.targets.test_lio_driver
Add mock for cinder-rtstool call in tests.targets.test_lio_driver

Unit tests in tests.targets.test_lio_driver are calling out to
cinder-rtstool.
change-id Ic25828361d9c30c4e1aa37b630d8ad272a78977b skips this
unit test to avoid failure of tests.
This patch reverts this change and adds mock for calling of
cinder-rtstool to reenable the unit tests.

Change-Id: I11dc07f692b5ba07484595c980f82bbdd2140d24
Closes-Bug: #1411029

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