Remove unused cache functions from token.core
Remove unused cache functions from token.core

With the move of functionality from token.core to token.persistence
the cache functions and import are no longer needed in token.core.

Change-Id: I97c96fff64b5c952155c4054df05b1b3ec3a83c5

klmitch/keystone,MaheshIBM/keystone,roopali8/keystone,rajalokan/keystone,idjaw/keystone,blueboxgroup/keystone,ilay09/keystone,dims/keystone,roopali8/keystone,vivekdhayaal/keystone,promptworks/keystone,vivekdhayaal/keystone,UTSA-ICS/keystone-kerberos,ging/keystone,idjaw/keystone,rajalokan/keystone,jamielennox/keystone,takeshineshiro/keystone,jumpstarter-io/keystone,ajayaa/keystone,blueboxgroup/keystone,vivekdhayaal/keystone,mahak/keystone,ajayaa/keystone,jonnary/keystone,nuxeh/keystone,klmitch/keystone,dims/keystone,jumpstarter-io/keystone,dstanek/keystone,takeshineshiro/keystone,himanshu-setia/keystone,ilay09/keystone,dstanek/keystone,openstack/keystone,ging/keystone,mahak/keystone,promptworks/keystone,promptworks/keystone,maestro-hybrid-cloud/keystone,nuxeh/keystone,rushiagr/keystone,rajalokan/keystone,MaheshIBM/keystone,ilay09/keystone,jumpstarter-io/keystone,jamielennox/keystone,cernops/keystone,maestro-hybrid-cloud/keystone,openstack/keystone,openstack/keystone,himanshu-setia/keystone,rushiagr/keystone,UTSA-ICS/keystone-kerberos,cernops/keystone,jonnary/keystone,dstanek/keystone,mahak/keystone,rushiagr/keystone,nuxeh/keystone