Configure Horizon to use SSL-enabled Keystone

SSL can be enabled in Keystone when devstack is executed.
Horizon was not being configured to use the SSL port so
authentication was failing.

Change-Id: I253766d359aaab0bd1f844a8a637adc77e8eee2b
Closes-Bug: 1293749
Merge "Configure Horizon to use SSL-enabled Keystone"