Bug 1068 fixed for auth_url in keystone

When we pass auth_url in nbi.cfg -> [authentication], the auth_url is used by password manager
but not by keystone http client. Need to pass auth_url to httpclient so that it uses auth_url
instead of https://keystone:5000 which is in service catalog of keystone.
Added http://keystone:5000/v3 to docker files.
Added regex validation for auth_url.

Change-Id: Ie3e144dd826e73a27c25f917cf54e64cf4c22207
Signed-off-by: K Sai Kiran <saikiran.k@tataelxsi.co.in>