Add FileReader class
Allow Section.new to take a hash of attributes
Let Composer#compose create sections using 'section do..end'
Add filename property to Composer
Move file_writing to GWT::compose method
Move file method from module wide method into Composer
Set up and run bundler
Add Runner class, which calls Composer
Set up cucumber and add bin method to drive whole composition process
Remove debugging code
Move run_file from bin to GWT; Make bin/git_writing_tool actually work