Lcg/ruby 2.1.3 windows

- bump default nokogiri
- install pre-built nokogiri binaries on windows (compiling it is broken, the internet will yell at you if you try)
- add widows support to rubygems since rubygems has a bug in 2.2.2 that breaks the mingw platform detection and at a minimum breaks installing nokogiri binaries
- add 2.1.3 binaries for ruby and devkit
- add md5 for ruby 2.1.3 for unix as well