Fix docstring and remove unused variable
Fix docstring and remove unused variable

Fix error docstring and remove unused variable 'volume ' in
VolumeTransferTestCase.

Change-Id: I6c98af30df88b8f19c23ef5e38e4b5b2eef7436c
Closes-Bug: #1272182

tlakshman26/cinder-new-branch,j-griffith/cinder,duhzecca/cinder,manojhirway/ExistingImagesOnNFS,duhzecca/cinder,nikesh-mahalka/cinder,CloudServer/cinder,tlakshman26/cinder-bug-fix-volume-conversion-full,mahak/cinder,Akrog/cinder,dims/cinder,tlakshman26/cinder-bug-fix-volume-conversion-full,manojhirway/ExistingImagesOnNFS,Paul-Ezell/cinder-1,sasukeh/cinder,hguemar/cinder,github-borat/cinder,saeki-masaki/cinder,Accelerite/cinder,apporc/cinder,bswartz/cinder,spring-week-topos/cinder-week,JioCloud/cinder,tlakshman26/cinder-https-changes,dims/cinder,blueboxgroup/cinder,tlakshman26/cinder-https-changes,Paul-Ezell/cinder-1,eharney/cinder,nikesh-mahalka/cinder,julianwang/cinder,nexusriot/cinder,Thingee/cinder,scottdangelo/RemoveVolumeMangerLocks,rakeshmi/cinder,Datera/cinder,Thingee/cinder,openstack/cinder,blueboxgroup/cinder,winndows/cinder,julianwang/cinder,tlakshman26/cinder-new-branch,saeki-masaki/cinder,sasukeh/cinder,potsmaster/cinder,Datera/cinder,nexusriot/cinder,Hybrid-Cloud/cinder,NeCTAR-RC/cinder,Akrog/cinder,abusse/cinder,openstack/cinder,cloudbase/cinder,winndows/cinder,hguemar/cinder,CloudServer/cinder,petrutlucian94/cinder,Nexenta/cinder,petrutlucian94/cinder,j-griffith/cinder,Nexenta/cinder,rakeshmi/cinder,takeshineshiro/cinder,spring-week-topos/cinder-week,apporc/cinder,scality/cinder,NetApp/cinder,potsmaster/cinder,leilihh/cinder,takeshineshiro/cinder,scality/cinder,phenoxim/cinder,cloudbase/cinder,JioCloud/cinder,Thingee/cinder,scottdangelo/RemoveVolumeMangerLocks,bswartz/cinder,NetApp/cinder,ge0rgi/cinder,mahak/cinder,Accelerite/cinder,eharney/cinder,leilihh/cinder,redhat-openstack/cinder,NeCTAR-RC/cinder,github-borat/cinder,phenoxim/cinder,alex8866/cinder,redhat-openstack/cinder,alex8866/cinder,abusse/cinder,Hybrid-Cloud/cinder