use 'exc_info=1' instead of import traceback
use 'exc_info=1' instead of import traceback

We need store traceback message in log sometime. Python logging module
already provide a argument to do that. For example, we could:

logger.error('msg', exc_info=1)
logger.debug(e, exc_info=(type_,value_,tb))
logger.exception('msg') # exception add exc_info automaticly

Change-Id: Iaf541e4f4ea139d9315ac1990f0e6079c8f8a20d

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