Add the parallel_tests gem for running rspecs in parallel

Removing the spec.opts file which references --loadby which parallel_rspec has
trouble with
Add .rspec to define shared RSpec preferences
Major refactor to improve add test coverage to the $jenkins_plugins fact

Not only does this support versions with dashes in it, it opens up the
possibility for us to include even MORE facts in the module! YAY

Fixes #90
Merge pull request #104 from rtyler/edgar/facter-test-coverage

Add test coverage for the $jenkins_plugin fact