Revert "Add 2.1.0 and ruby-head to .travis.yml"
Revert "Add 2.1.0 and ruby-head to .travis.yml"

This reverts commit 13ad9ed2b1d1f99900e4aef9084bf9024b2b1103.

id774/fastladder,toshimaru/fastladder,onk/fastladder,fastladder/fastladder,ykzts/fastladder,id774/fastladder,ykzts/fastladder,ykzts/fastladder,onk/fastladder,toshimaru/fastladder,fastladder/fastladder,onk/fastladder,id774/fastladder,toshimaru/fastladder,fastladder/fastladder