(PUP-2777) Bundler Windows x64 workflow

 - Ensure that Bundler loads proper gemset whether on x86 or x64, based
   on what is defined in project_data.yaml
 - Note that latest FFI compatible gems have been added to x64 out of
   necessity, but the code fails tests, and is not yet compatible with
   Ruby 2 changes / gem updates.
 - Gem versions for Ruby 1.9.x were kept the same, and will be upgraded
   as part of verifying gem compatibility when updating 1.9.x branch
   to use latest FFI compatible gems.
Meaning I think I like this approach a bit better, it's cleaner.