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.
The `if` condition here doesn't match the context description above. Currently, it will match version 4.0 or greater.

I think the context description could be amended to 'Puppet >= 3.7', since the behaviour in version 4.0 is unlikely to change.