Use Hadoop 2.2.0 instead of 2.1.0-beta
Travis/rvm no longer supports specific JRuby versions
More failsafe computation of hadoop home

This should not be tricked into using the tar ball instead of the dir
Fix test_project setup

- Ensure gem set is created in correct ruby
- Ensure bundler is installed in the gemset
Use bundle exec to ensure right gem versions are used
Specs use JRUBY_VERSION instead of RUBY_VERSION

As RUBY_VERSION in general is not guaranteed to contain the version, and
on Travis in particular is jruby-$JRUBY_VERSION-d1[89], it does not make
sense to rely on it in the tests.
Merge branch 'travis_support'