Print, but don't fail on deprecation notice

A simple change so that deprecation notices are printed, but don't cause test failures. A possible fix for issue #27.
I think we can probably relax the `if` condition and `context` description to only test for Puppet version 3.7 and above as we don't yet know how Puppet version 4.0 will behave. We can always amend the tests when the time comes to add support for Puppet 4.0.