Enable testing on JRuby in Travis CI
Enable testing on JRuby in Travis CI

This was previously disabled due to a bug in conversion of binary strings to UTF-8.
It appears that the bug is fixed now (the test code which L. Segal had posted on
the JRuby bug tracker runs correctly in JRuby 1.7.9).

lsegal/yard,lsegal/yard,thomthom/yard,amclain/yard,thomthom/yard,amclain/yard,lsegal/yard,amclain/yard,thomthom/yard