15586 - rdoc::usage failing on ruby 1.9.3

This is built from an earlier closed pull request ([#299](https://github.com/puppetlabs/facter/pull/299)). Since <tt>RDoc::Usage</tt> is gone in Ruby 1.9.x, the displaying & parsing of options has been converted to Trollop.

The original work was done by @apenney and a short conversation with @jeffmccune resulted in pulling out the vendored copy of Trollop and replacing it with a dependency. This has been reflected in the Gemfile as well as the gemspec.

While this includes the relevant changes to the banner, it does not include the RDoc changes to [bin/facter](https://github.com/apenney/facter/commit/a4fa9121971e5c7d08be93659b64bb3ffc89d01e). I thought someone with a little more concern for the tool might want to figure out what stays and what goes in the user-face executable.

Ashley also noted the follow major change from existing <tt>-h|--help</tt> behavior:

* Additional support for things like <tt>--no-trace</tt> and <tt>--no-debug</tt>, not that we need that with the current set of options.