Downgrade bundler version
Downgrade bundler version

Since either CircleCI or Heroku have native support for bundler 2.0 lets
wait with this upgrade.

It was possible to fix, but I felt that there where too many ad-hoc
solutions for it to be a good way forward. So lets wait until they added
bundler 2.x.

barsoom/pipeline,barsoom/pipeline,barsoom/pipeline,barsoom/pipeline