JsonGem and JsonPure adapters should work with the yajl-ruby compatible
::JSON implementations.

    * yajl-ruby's "yajl/json_gem" overwrites ::JSON implementation in a
       "compatible" way, but the options expected are different.
       yajl-ruby expects :symbolize_keys, while the json gem expects
       :symbolize_names. yajl-ruby has patched this issue in HEAD, for v2 of the gem
       which is unreleased, but it doesn't appear they will backport to v1.1.

      https://github.com/brianmario/yajl-ruby/issues/94
      https://github.com/brianmario/yajl-ruby/pull/105