Wrong usage of "a/an"
Wrong usage of "a/an"

Wrong usage of a in the mesage:
"auth_url is a authentication URL of remote Keystone"
Should be:
"auth_url is an authentication URL of remote Keystone"
Wrong usage of an in below mesage:
"id is an unique, user defined identifier"
Should be:
"id is a unique, user defined identifier"
Totally 4 occasions in Keystone base code.

Change-Id: I3b1de967a1601d4da64fc97afaa65c54d555b3ed

mahak/keystone,rajalokan/keystone,rajalokan/keystone,cernops/keystone,dims/keystone,ilay09/keystone,klmitch/keystone,rajalokan/keystone,openstack/keystone,dims/keystone,himanshu-setia/keystone,ilay09/keystone,ilay09/keystone,openstack/keystone,klmitch/keystone,mahak/keystone,openstack/keystone,himanshu-setia/keystone,cernops/keystone,mahak/keystone