pin sqlalchemy to 0.7
pin sqlalchemy to 0.7

sqlalchemy 0.8.0b1 breaks some dependencies such as sqlalchemy-migrate, pin the version until we fix them

Fixes bug #1073569

Change-Id: I6620276bf8f0a7cbc1d51aa226cd33c512e59a48

rodrigods/keystone,openstack/keystone,maestro-hybrid-cloud/keystone,blueboxgroup/keystone,vivekdhayaal/keystone,rickerc/keystone_audit,kwss/keystone,rickerc/keystone_audit,kwss/keystone,jonnary/keystone,promptworks/keystone,jumpstarter-io/keystone,ntt-sic/keystone,cernops/keystone,MaheshIBM/keystone,rodrigods/keystone,idjaw/keystone,ntt-sic/keystone,cbrucks/Federated_Keystone,cbrucks/Federated_Keystone,rushiagr/keystone,cloudbau/keystone,klmitch/keystone,reeshupatel/demo,rushiagr/keystone,citrix-openstack-build/keystone,jumpstarter-io/keystone,ilay09/keystone,roopali8/keystone,cloudbau/keystone,ilay09/keystone,reeshupatel/demo,derekchiang/keystone,dsiddharth/access-keys,citrix-openstack-build/keystone,ging/keystone,UTSA-ICS/keystone-kerberos,ntt-sic/keystone,rickerc/keystone_audit,idjaw/keystone,maestro-hybrid-cloud/keystone,promptworks/keystone,vivekdhayaal/keystone,derekchiang/keystone,openstack/keystone,townbull/keystone-dtrust,cernops/keystone,promptworks/keystone,townbull/keystone-dtrust,ilay09/keystone,jamielennox/keystone,rushiagr/keystone,takeshineshiro/keystone,mahak/keystone,dsiddharth/access-keys,ajayaa/keystone,openstack/keystone,dims/keystone,rajalokan/keystone,dstanek/keystone,dstanek/keystone,klmitch/keystone,nuxeh/keystone,JioCloud/keystone,cbrucks/Federated_Keystone,UTSA-ICS/keystone-kerberos,mahak/keystone,townbull/keystone-dtrust,cloudbau/keystone,citrix-openstack-build/keystone,mahak/keystone,blueboxgroup/keystone,dims/keystone,kwss/keystone,JioCloud/keystone,himanshu-setia/keystone,nuxeh/keystone,jamielennox/keystone,reeshupatel/demo,jumpstarter-io/keystone,rajalokan/keystone,vivekdhayaal/keystone,himanshu-setia/keystone,dstanek/keystone,roopali8/keystone,nuxeh/keystone,rajalokan/keystone,dsiddharth/access-keys,jonnary/keystone,ajayaa/keystone,ging/keystone,takeshineshiro/keystone,MaheshIBM/keystone,derekchiang/keystone