Change headers to be byte string friendly
Change headers to be byte string friendly

The wsgi pipeline requires that headers be strings, but the
urls are coming from the sql backend as unicode.

Change-Id: I711b3a02b51062b2f698200a6eff50af4fe0ffab

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