Test with ruby 2.0 in travis-ci, and allow_failure
Test with ruby 2.0 in travis-ci, and allow_failure

sideci-sample/sideci-sample-rabl,infertux/rabl,Jyaasa/rabl,Jyaasa/rabl,bholzer/rabl,Jyaasa/rabl,sideci-sample/sideci-sample-rabl,infertux/rabl,nesquena/rabl,bholzer/rabl,nesquena/rabl,nesquena/rabl,zoyi/rabl,bholzer/rabl,zoyi/rabl,infertux/rabl,zoyi/rabl