Add ruby branch to master

[jeremydouglass]

Currently I'm slowly collecting some sketches that @monkstone has posted to the wiki / and to the Processing forums / and here (#38) into a "ruby" branch on this repo, with sketches organized in /examples/ruby.

However, the ruby examples will need some kind of a README letting people know that these do not currently work in PDE by default, and will need to be run with JRubyArt -- it should probably just link to https://ruby-processing.github.io/JRubyArt/