horizon 18.6.0 release

meta:version: 18.6.0
meta:diff-start: -
meta:series: victoria
meta:release-type: release
meta:pypi: no
meta:first: no
meta:release:Author: Ivan Kolodyazhny <e0ne@e0ne.info>
meta:release:Commit: Ivan Kolodyazhny <e0ne@e0ne.info>
meta:release:Change-Id: Ia474361c6f1c91e38c8f956733223280f7c4727b
meta:release:Code-Review+1: Vishal Manchanda <manchandavishal143@gmail.com>
meta:release:Code-Review+2: Hervé Beraud <hberaud@redhat.com>
meta:release:Code-Review+2: Thierry Carrez <thierry@openstack.org>
meta:release:Workflow+1: Thierry Carrez <thierry@openstack.org>