lib/swift: the s3_token middleware should be provided by keystonemiddleware
lib/swift: the s3_token middleware should be provided by keystonemiddleware

Recently, keystoneclient.middleware has been moved from keystoneclient to
keystonemiddleware. The latter should be used.

Change-Id: Ib9489a21b988b32fc17399c08eeb60862efae034
Closes-Bug: #1452315

dirkmueller/devstack,openstack-dev/devstack,group-policy/devstack,rushiagr/devstack,upadhyay-prashant/devstack,richliu/devstack,samgoon/devstack,liuquansheng47/devstack,eharney/devstack,LoHChina/devstack,mmasaki/devstack,NaokiMiyata/devstack,rushiagr/devstack,j4/devstack,richliu/devstack,mssumanth/devstack,parul24/devstack,pacinete/devstack,liuquansheng47/devstack,bigswitch/devstack,costingalan/devstack,flavio-fernandes/devstack,prithivm/branch01,vsham20/devstack,avvocatodemarchis/devstack,TwinkleChawla/devstack,j4/devstack,parul24/devstack,bq-xiao/devstack,upadhyay-prashant/devstack,olivierlemasle/devstack,TwinkleChawla/devstack,vishnugonela/devstack,samgoon/devstack,andrewrothstein/devstack,dtroyer/devstack,mc2014/devstack,CloudServer/devstack,costingalan/devstack,pombredanne/devstack,eharney/devstack,avvocatodemarchis/devstack,Mahito/devstack,vishnugonela/devstack,pczerkas/devstack,mssumanth/devstack,LoHChina/devstack,CloudServer/devstack,olivierlemasle/devstack,vsham20/devstack,bljgaurav/openstack-test,pacinete/devstack,bigswitch/devstack,andrewrothstein/devstack,dtroyer/devstack,ozamiatin/devstack,prithivm/branch01,thomasem/devstack,mmasaki/devstack,wenhuizhang/devstack,flavio-fernandes/devstack,noironetworks/devstack,Mahito/devstack,atulpatil301/devstack,nawawi/openstack,varunarya10/devstack,bq-xiao/devstack,openstack-dev/devstack,ozamiatin/devstack,varunarya10/devstack,bswartz/devstack,HPCHub/devstack,dirkmueller/devstack,nawawi/openstack,pczerkas/devstack,atulpatil301/devstack,group-policy/devstack,bljgaurav/openstack-test,NaokiMiyata/devstack,mc2014/devstack,pombredanne/devstack,bswartz/devstack,herrsechs/devstack,wenhuizhang/devstack,noironetworks/devstack,thomasem/devstack,HPCHub/devstack,herrsechs/devstack