Add json2.js polyfill (v2014-02-04; with module skip function)

Source from https://github.com/douglascrockford/JSON-js/blob/3d7767b/json2.js

* Deprecate jquery.json which is a little dated and less efficient
  because it always downloads the entire polyfill to the client
  even if it isn't needed. We also can't add a skip function to
  jquery.json because it exposes a different interface ($.toJSON
  instead of JSON.stringify).

* Update 'mediawiki.inspect' to use 'json' instead.

* Update 'jquery.jStorage' to use 'json' instead (doesn't need
  a change to its code as it looks for either JSON.stringify or
  $.toJSON by design).

Change-Id: I8978be3491b08fbbfd83f1306e816b1b20f16161
Merge "Add json2.js polyfill (v2014-02-04; with module skip function)"