Revert "bump version 1.13"

This reverts commit 2661a03b5dc3c809b9da963dc11b791a39878560.
Revert "jruby 1.7.15"

This reverts commit 4d61e90ccb58d86bdd2e5d74c95e492f7f177667.
Revert "bump version 1.13.beta.1"

This reverts commit 39e5b14e9e28f2025936975e3f02f3e09a303f5c.