Update gems
Pull foodcritic from github so that we get a newer nokogiri

* nokogiri ~>1.5.4 would not install on OSX 10.9.3
Fix constant name Rubocop -> RuboCop
Like preferences sub-directories instead of individual files

* this behavior is more like the scripts in pivotal/Pivotal-Preferences-RubyMine
* original sub-directories are backedup to <dirname>.bak.<timestamp>
RuboCop ignores cookbooks/ and tmp/