Add mistral-extra package
Add mistral-extra package

mistral-extra is a new dependency for projects that integrate
with Mistral.  It provides tools and examples and will include
all of the OpenStack actions.  It is added to to tripleo-common
in review: https://review.openstack.org/#/c/523540/

Package review is in https://bugzilla.redhat.com/show_bug.cgi?id=1482108

The under-review tag has been added until the initial import has been
completed.

Change-Id: Ibc077fd746cb34343cb0b92663fa9727d10f3a16

redhat-openstack/rdoinfo,javierpena/rdoinfo