Ruby development console.
Octopress::Configuration is now a class, rather than a module.

The previous system was very unforgiving about where the configuration directory
lay. This commit allows the configuration directory to be set through a config_directory
instance variable on the Octopress::Configuration class, in the event that this directory
ever needs to be changed (e.g. for testing).
Updated Rakefile to handle Octopress::Configuration as a class.
Specifying an exact version for rdiscount.
Testing now in lib/, added a supporting Gemfile and Rakefile