Make rbx-2.1.1 build run on travis

This enables the rbx-2.1.1 build to run on travis.  @jnicklas : 2.1.0 on travis appears to just be missing since it doesnt even install, so I removed it from travis.yml completely.  2.0.0 appears not to install the ruby standard library since 'gem --version' errors our before we have a chance to run any scripts to install anything so I've moved that to allowed failures.   jruby is failing because stdout appears to be buffered so travis doesnt see any status output from rspec for 10 minutes and aborts the run.  Any ideas on that?