User email is optional and can be absent

cherry-picked from faf5b2aead067ab00a936249085f65886edcb483
cherry-picked from 19566878b24925bf423fe9588652ea59322af58d

Change-Id: Idff0f7c33bcaee29c7d1e7be415eb6b5b29b5b1a
Related-Bug: #1260423
Merge "User email is optional and can be absent" into stable/grizzly
Merge branch 'stable/grizzly' of https://github.com/openstack/horizon into grizzly/router_rules