Revert "Use earlier version of rubygems to avoid bundler fatal error on 1.8.7"
Revert "Use earlier version of rubygems to avoid bundler fatal error on 1.8.7"

This reverts commit ab886eb3be8f197ce628419461bbe03c28cd8d21.

The bug has been fixed in rubygems, so that workaround is not needed
anymore.

monterail/multiblock