Fix include_class deprecation warning. Use contain_class instead.

Change-Id: I9ab9e1d72a06b2de0d63601795b0902e53f330b6
(cherry picked from commit eefaf9ca54a71d16181e687b216db9e9930e97df)
Merge branch 'stable/havana' of https://github.com/stackforge/puppet-swift into havana