Issue #57 Require puppet-rspec version 0.1.6

In puppet-rspec versions >= 1.0.0, a parameter was added to the
catalogue method.  This broked a number of the rspec tests.  By
requiring puppet-rspec version 0.1.6 in .gemfile, you can get the tests
to pass again.
Issue #57 Update rspec-puppet in .gemfile.travis

Updating the gemfile used by TravisCI to use the correct version of the
rspec-puppet gem.

Also updated .gitignore to ignore .gemfile.travis.lock
Merge pull request #57 from Element84/Issue57

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