Revert "Merge pull request #887 from heroku/multi_json"

This reverts commit edf72a00caa4a642bd3b88e152a66b7b0aa6a63b, reversing
changes made to fd73503abdd949f095b09b837c5e41ad9ed5eb38.

Conflicts:
	lib/heroku/helpers.rb
v3.6.0