Define ruby version

When you do "bundle install", bundler will pull a bunch of gems out of
rubygems.org and build your requirements into Gemfile.lock.  If you
don't define your ruby version, you run the risk of running 1.9.3
locally, but 2.1 on Heroku (for example).

Picked 2.0.0 at random.  Feel free to change it to whatever you like
("ruby -v" at the prompt will tell you what version you're running
locally)
Add simplecov to gather code coverage metrics

At the prompt, run "bundle exec rspec" and it will generate a /coverage
directory at the root of your project.  This will show you your code
coverage, paths missing test coverage, etc.
Don't include simplecov results in git