RSpec HTML inspired formatter and formatter restructure

This pull request includes a new formatter where I took the output of some RSpec tests, used the same HTML, but tweaked it a bit.  I call it rspec_html, even though it isn't **exactly** the RSpec HTML, but it visually looks the same.

I also restructured the way a new formatter is created.  When I wrote the RSpec HTML formatter I had to do the following:
* Write my formatter
* Write specs for my formatter
* Update README.md
* Update the jasmine env_comments.rb
* Update the mocha env_comments.rb
* Update the qunit env_comments.rb
* Update command_line.rb
* Make the Base formatter class auto load it
* Update the command_line_spec.rb (which I actually missed in my first commit)

This seemed excessive to me, so I made the process look like this:
* Write my formatter
* Write specs for my formatter
* Update README.md
* Register the formatter in the Base formatter class

All the other steps take the definition from the Base formatter class and utilize it for their own output.

I would be happy to discuss any changes you would like before getting this pull request accepted.