Correct backup_type param description
Correct backup_type param description

Nova client requires providing backup_type, this backup_type is only a tag
which used for filtering images, so it could be any user-defined tag.

This patch corrects param description in _rotate_backups to avoid misleading of
restricting 'daily'/'weekly'.

Related-Bug: #1298157
Change-Id: I1f73e753524231cd89b37fe06bd9e3934371a986

MountainWei/nova,whitepages/nova,zzicewind/nova,iuliat/nova,nikesh-mahalka/nova,barnsnake351/nova,cyx1231st/nova,vmturbo/nova,devendermishrajio/nova_test_latest,noironetworks/nova,CEG-FYP-OpenStack/scheduler,edulramirez/nova,ruslanloman/nova,BeyondTheClouds/nova,hanlind/nova,CCI-MOC/nova,raildo/nova,TwinkleChawla/nova,apporc/nova,iuliat/nova,NeCTAR-RC/nova,raildo/nova,Francis-Liu/animated-broccoli,Juniper/nova,mikalstill/nova,sebrandon1/nova,JioCloud/nova_test_latest,watonyweng/nova,zhimin711/nova,jianghuaw/nova,hanlind/nova,jianghuaw/nova,rajalokan/nova,gooddata/openstack-nova,klmitch/nova,JioCloud/nova_test_latest,dims/nova,rajalokan/nova,mahak/nova,rajalokan/nova,LoHChina/nova,hanlind/nova,BeyondTheClouds/nova,akash1808/nova_test_latest,rahulunair/nova,LoHChina/nova,JianyuWang/nova,cloudbase/nova,varunarya10/nova_test_latest,shail2810/nova,Francis-Liu/animated-broccoli,openstack/nova,cloudbase/nova,watonyweng/nova,sebrandon1/nova,cyx1231st/nova,cernops/nova,Juniper/nova,ted-gould/nova,cloudbase/nova,barnsnake351/nova,apporc/nova,j-carpentier/nova,felixma/nova,mikalstill/nova,zzicewind/nova,noironetworks/nova,devendermishrajio/nova,MountainWei/nova,vmturbo/nova,takeshineshiro/nova,mmnelemane/nova,rahulunair/nova,klmitch/nova,alaski/nova,gooddata/openstack-nova,Juniper/nova,yosshy/nova,dims/nova,fnordahl/nova,scripnichenko/nova,scripnichenko/nova,cernops/nova,CCI-MOC/nova,TwinkleChawla/nova,yosshy/nova,openstack/nova,fnordahl/nova,whitepages/nova,vmturbo/nova,bigswitch/nova,isyippee/nova,Juniper/nova,bigswitch/nova,shail2810/nova,BeyondTheClouds/nova,sebrandon1/nova,openstack/nova,isyippee/nova,klmitch/nova,varunarya10/nova_test_latest,alaski/nova,devendermishrajio/nova,devendermishrajio/nova_test_latest,rahulunair/nova,phenoxim/nova,nikesh-mahalka/nova,ruslanloman/nova,mahak/nova,edulramirez/nova,vmturbo/nova,felixma/nova,takeshineshiro/nova,mahak/nova,ted-gould/nova,NeCTAR-RC/nova,zhimin711/nova,akash1808/nova_test_latest,jianghuaw/nova,CEG-FYP-OpenStack/scheduler,gooddata/openstack-nova,jianghuaw/nova,rajalokan/nova,phenoxim/nova,JianyuWang/nova,klmitch/nova,mikalstill/nova,mmnelemane/nova,j-carpentier/nova,cernops/nova,gooddata/openstack-nova