Pact v3 specification implementation for Pact Ruby

[ThomasKoppensteiner]

Please implement the pact v3 specification for Ruby (MRI and JRuby).

This ticket is a starting point. Please feel free to convert it to a GitHub project or a milestone.

[YOU54F]

closing in favour of #318, as it will be easier for me to track

thanks for raising

[YOU54F]

ps we don't officially support jruby, it hasn't been tested in many moons, and therefore support may be dropped completely if it doesn't work with ffi interop with the pact_ffi native library. see #317