all? not working in JRuby 1.7.5+. Configure Travis

That's the reason the travis build is failing on jruby, the override of `each` in Collection stopped working after 1.7.4
https://github.com/jruby/jruby/issues/1265
Merge pull request #2429 from maestrodev/travis-jruby

all? not working in JRuby 1.7.5+. Configure Travis