Instead of keeping a local copy of spec_helper_acceptance.rb and
requiring updates to all modules for any change, we can move it into the
common helper gem and require it from there. This will make it easier to
create and review changes that affect all puppet modules. Also change
the Gemfile to look for the gem in the local workspace if running in a
zuul environment.
Change-Id: Ie2c2210ddb22b948faca86668d17529f4803348b
Add a xenial nodeset and update the spec helper to install puppet 3 from
the Ubuntu repos instead of from puppetlabs.
Change-Id: I3ea01f9dd4ee9217861ff3e28aac3b92a9f00fa3