NO-JIRA: Creates an upstream source tarball for the Ruby language bindings.

Generates a tarball that includes the Swig descriptor for the Ruby
bindings, as well as the public Ruby APIs that sit on top of the Swig
APIs, and various documentation.

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1430466 13f79535-47bb-0310-9956-ffa450edef68