Update our jruby to 1.6.0

We reverted our jruby jar to 1.0.3 because of licensing issues in 1.5.x. The jruby crew fixed the licensing issues in 1.6.0RC2 (which is released but not yet in a mvn repo). This issue is about updating our ruby. The old ruby 'works' but is bad in many ways; bad parse errors, missing language support that made us redo a bunch of our script to not use import (and removal of TestShell, our unit test that ran jruby tests).

This issue is about updating our jruby and in particular, reenabling the TestShell unit test removed by HBASE-3374.