tell users which username to use for LDAP auth

users log in in with creds where "username" is ambiguous.
tell them which one to use.

rename graphite apache template to .erb

Change-Id: Ie105ea084cf3290dd4d85b856c279896836a9d66
RT 4965 antimony addition

Change-Id: I0a3351788304f4e3df9d20664f5f093a65e64ee1
Merge "tell users which username to use for LDAP auth" into production
Merge "RT 4965 antimony addition" into production