Refs #2 - Fixed error while starting middleman

Added check for type of path, when trying to require
path.
Refs #2 - Rake tasks were fixed

Added tasks right into Rakefile.
Refs #2 - Fixed `rake github:pull_request` command
Merge pull request #2 from OrelSokolov/g2_ooa_error_with_middleman

Error when starting middleman