(MODULES-433) Moved from `#include_class` to `#contain_class`

Removed per the DEPRECATION warning [1].  Since this repo does not include a
Gemfile.lock, and the Gemfile does not have version requirements, `bundle`
will install the most recent upstream version of the gems.

I personally suggest adding the Gemfile.lock to the repo.  This will guarantee
the exact gem deps are installed on each execution of `bundle`.  However, for
now will keep things as is, and simply added a .gitignore.

    [1] DEPRECATION: include_class is deprecated. Use contain_class instead. Called from /Users/jodewey/.rvm/gems/ruby-1.9.3-
    p484/gems/rspec-puppet-1.0.1/lib/rspec-puppet/matchers/include_class.rb:7:in `block (2 levels) in <module:ManifestMatchers>'.