Rename dependencies/ruby/ruby-2.0.0-p353 for Win64

@macumber @axelstudios My win64 build of ruby fails because it can't find Makefile.sub:

    Error copying file "C:/Users/jason/Projects/OpenStudio/dependencies/ruby/ruby-2.0.0-p481/Makefile.sub"
    to "C:/Users/jason/Projects/OpenStudio/build/Ruby-prefix/src/Ruby/win32/Makefile.sub".

The directory Makefile.sub is in is named "ruby-2.0.0-p353", so I changed it to "ruby-2.0.0-p481" to match the name in CMakeLists.txt