Add MRI 2.1.0 to the mix
Add MRI 2.1.0 to the mix

And allow it to fail (for now).

kidaa/travis-core,jantman/travis-core,kidaa/travis-core,Tiger66639/travis-core,Tiger66639/travis-core,travis-ci/travis-core,jantman/travis-core,GistIcon/travis-core,developerfm/travis-core,GistIcon/travis-core,developerfm/travis-core,final-ci/travis-core,GistIcon/travis-core,developerfm/travis-core,final-ci/travis-core,final-ci/travis-core,Tiger66639/travis-core,travis-ci/travis-core,travis-ci/travis-core,kidaa/travis-core