Revert "Rails 4.2 gemfile needs a modern JSON version"
Revert "Rails 4.2 gemfile needs a modern JSON version"

This reverts commit 4fb803a9b3f58dd4c63ae203edfc04ea9c8f3078.

Rails 4.2 is locked to JSON 1.8

getsentry/raven-ruby,looker/raven-ruby