Revert "Try again to fix Travis-CI"

This reverts commit d7267db3d844e741af6302d0bcce790dd0a2d2f6.
Revert "Try to fix Travis-CI"

This reverts commit 19f8d6134b63e518824a60850a534944b2772c38.
Revert "Use Rubinius HEAD in Travis-CI"

This reverts commit bfc1c124c869b6c3fe19aa8b16af15eafc1f0acf.
Revert "Switch to Rubinius"

This reverts commit 739ae76a92148c864f593fb211f263ed74597aa5.