Bundler and gemspec

- Rename project to varnisher
- Use Bundler to describe and manage dependencies
- Create a gemspec allowing varnisher to be installed as a gem
- Restructure files to be gem-friendly (move libs to lib/varnisher,
  rather than just lib/; move binaries to bin/).
Rewrite README to include gem-centric installation instructions
Merge pull request #2 from robmiller/gemspec

Bundler and Gemspec