added role to pin packages

This new role is now providing the ability for a user to pin apt
packages as they see fit. The idea is to allow someone to implement
pinning in a generic way that can be represented as a global variable
or as a hostvar. The new role has been added to all install roles as
a dependency which will allow it to ensure that packages are pinned
everywhere as would be expected.

Change-Id: I354e8515570fa7174366ba57d57aece3c304568e

meta/main.yml

@@ -30,5 +30,6 @@ galaxy_info:
     - development
     - openstack
 dependencies:
+  - apt_package_pinning
   - openstack_openrc
   - pip_lock_down