minor: adding jruby-1.7.6 release

Adding yesterday's JRuby release:
http://jruby.org/2013/10/22/jruby-1-7-6

The JRuby team is moving to a slightly more aggressive release schedule for these patch level releases. The goal is smaller and a bit more frequent. We can expect a new one every ~3 weeks or so until their next major release.