Make trust manager raise formatted message exception
Make trust manager raise formatted message exception

Keystone Exception doesn't support the following use:
raise exception.Forbidden(_('%(xx)d %(yy)d]'), xx=1, yy=2)
This can lead to a bug that we will get a unformatted message when
error happens.

Change-Id: I8a9d4b61eaed8575fe1473ccf5d54a4efe752f21
Closes-Bug: #1413905

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