Add tripleo::packages

Add tripleo::packages

This adds a new class to help configure package installation
and upgrades.

The previous approach was to use a global package declaration
at the top of each manifest within the tripleo-heat-templates.

The new approach is to use a Package collector (<| |>) to
allow us to configure the package provider within a
class. This should help remove some of the duplicated logic
within the triplo-heat-template manifests and is
also a good fit for puppet-tripleo in that is generic
and unlikely to change that often.

In addition to installation this class also support upgrades
to puppet managed packages as well.

Change-Id: Ie8fbc344149bc8c9977e127de77636903607617a