avoid sub-classing ThreadLocal since it will leak in envs such as (warbled) .war apps

due JRuby classes being loaded from the (WEB-INF/lib) application loader ...
prevents such applications from correctly releasing class memory (e.g. on re-deploys)
docbk goal was broken - fix #1799 [skip ci]
Merge branch 'jruby-1_7' of jruby.org:jruby into jruby-1_7
Fix Encoding::Converter#inspect output

There was a missing closing chevron in the computed string.
Make Time#to_r consistent with MRI

Let's make JRuby matches the behavior of MRI when calling to_r on a Time
object. It used to return only the numerator of the Rational object if
the denominator was equal to 1.
Merge pull request #1772 from kares/thread-local-leak-1_7

avoid sub-classing ThreadLocal since it will leak in envs such as .wars
Merge with jruby-1_7