Addition of some context files

Add support for the user of Bundler to handle Gem dependencies, making setup easier. Added files:
Contributing.MD / Gemfile
Rdiscount may be included in the Jekyll installation as well (I think it ships with Marku, RedCarpet, Kramdown and rdiscount). I honestly haven't researched them that much, but if it can do smart quotes and dashes (-- to endash for example) I'm good. I like the table functionality, but it seems a little complicated when I can just markup a table in HTML. The one feature that is the in the original Markdown "spec" that I would like to see is replacing email addresses with Unicode entities (if that actually works to reduce SPAM).