Remove WritableLogger wrapper
Remove WritableLogger wrapper

With Eventlet 0.17.2, we can directly pass the logger
instance. This allows us to deprecate/remove the WritableLogger
class from oslo.log.

Change-Id: Ib7d193435584fc3631740058ed34b4df4ab23ad6
Closes-Bug: #1440773

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