Rubinius support for specs and travis-ci

Get specs passing locally for rbx-2.2.5 (latest as of this time).  Having issues on travis-ci because the build times out after 50 minutes.  I don't have this issue when running specs locally: the build finishes in 275.81 seconds on my MacBook Pro running Mavericks.  I'm not sure if the build time is related to hardware differences or OS difference on the travis-ci build servers.  I'd appreciate developers using Linux and Windows to test this out locally to try to narrow down the performance issues.

If we can't figure out why travis-ci is slower, then I'll have to add rbx to the allowed failures part of the build matrix, but the changes in this PR are still useful for rbx compatibility for those users who are interested and because it fixes some thread leaks in the specs.