s3api: use boto to get canonical string for signature
s3api: use boto to get canonical string for signature

Replace the homegrown function to get a canonical string for
signature.

smerritt/swift,orion/swift-config,iostackproject/IO-Bandwidth-Differentiation,Em-Pan/swift,shibaniahegde/OpenStak_swift,prashanthpai/swift,JioCloud/swift,gold3bear/swift,xiaoguoai/ec-dev-swift,notmyname/swift,bradleypj823/swift,dpgoetz/swift,smerritt/swift,mjwtom/swift,Khushbu27/Tutorial,matthewoliver/swift,levythu/swift,openstack/swift,Mirantis/swift-encrypt,hbhdytf/mac2,aerwin3/swift,mjzmjz/swift,thiagodasilva/swift,mja054/swift_plugin,nadeemsyed/swift,gold3bear/swift,mjwtom/swift,tsli/test,rackerlabs/swift,redhat-openstack/swift,ceph/swift,Intel-bigdata/swift,openstack/swift,Seagate/swift,hurricanerix/swift,smerritt/swift,williamthegrey/swift,daasbank/swift,AfonsoFGarcia/swift,maginatics/swift,nadeemsyed/swift,tipabu/swift,daasbank/swift,bouncestorage/swift,thiagodasilva/swift,VictorLowther/swift,anishnarang/gswift,takeshineshiro/swift,nadeemsyed/swift,tsli/test,mja054/swift_plugin,aerwin3/swift,hurricanerix/swift,citrix-openstack/build-swift,prashanthpai/swift,scality/ScalitySproxydSwift,Triv90/SwiftUml,openstack/swift,eatbyte/Swift,anishnarang/gswift,wenhuizhang/swift,citrix-openstack/build-swift,houseurmusic/my-swift,mja054/swift_plugin,Akanoa/swift,iostackproject/IO-Bandwidth-Differentiation,zackmdavis/swift,smerritt/swift,sarvesh-ranjan/swift,SUSE/swift,clayg/swift,matthewoliver/swift,matthewoliver/swift,notmyname/swift,zaitcev/swift-lfs,AfonsoFGarcia/swift,rackerlabs/swift,psachin/swift,takeshineshiro/swift,clayg/swift,clayg/swift,eatbyte/Swift,redbo/swift,Triv90/SwiftUml,bradleypj823/swift,zaitcev/swift-lfs,Seagate/swift,revoer/keystone-8.0.0,orion/swift-config,dencaval/swift,JioCloud/swift,notmyname/swift,shibaniahegde/OpenStak_swift,wenhuizhang/swift,NewpTone/StackLab-swift,zackmdavis/swift,redhat-openstack/swift,bkolli/swift,hbhdytf/mac2,hbhdytf/mac,dencaval/swift,Khushbu27/Tutorial,NeCTAR-RC/swift,nadeemsyed/swift,Mirantis/swift-encrypt,hurricanerix/swift,tipabu/swift,Intel-bigdata/swift,scality/ScalitySproxydSwift,larsbutler/swift,citrix-openstack-build/swift,psachin/swift,hbhdytf/mac2,tipabu/swift,tipabu/swift,Akanoa/swift,swiftstack/swift,notmyname/swift,levythu/swift,NewpTone/StackLab-swift,xiaoguoai/ec-dev-swift,Em-Pan/swift,hbhdytf/mac2,IPVL/swift-kilo,citrix-openstack-build/swift,NeCTAR-RC/swift,williamthegrey/swift,dpgoetz/swift,revoer/keystone-8.0.0,SUSE/swift,psachin/swift,hbhdytf/mac,bkolli/swift,VictorLowther/swift,mjzmjz/swift,clayg/swift,psachin/swift,hurricanerix/swift,ceph/swift,maginatics/swift,swiftstack/swift,redbo/swift,sarvesh-ranjan/swift,openstack/swift,matthewoliver/swift,swiftstack/swift,houseurmusic/my-swift,bouncestorage/swift,IPVL/swift-kilo,larsbutler/swift