PROTON-215: Added ruby interop test.

Added a ruby version of the interop test.
- Added convenience classes to Data to handle array, map, described and null.
- Added a Type object to describe Data types.

All tests (python, java, ruby) are passing.
- Disabled failing test in message_spec.rb, see PROTON-272

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1456613 13f79535-47bb-0310-9956-ffa450edef68