Select keystone endpoint url bases on SSL setting

When keystone is ssl enabled, (by setting ssl/enabled = TRUE in
keystone.conf) the keystone auth server is using HTTPS instead of HTTP
as the protocol. This patch generates the correct endpoint for the
keystone service calls.

In addition, if there is a defined 'admin_endpoint' in keystone.conf,
this setting will take precedence.

Change-Id: I23fe552808d8a959b0dff1c86989cf2aaa04582a
Merge "Select keystone endpoint url bases on SSL setting"