mediawiki.inspect: use $.toJSON & add workaround for FF oddity

mediawiki.inspect: use $.toJSON & add workaround for FF oddity

* Use $.toJSON rather than JSON.stringify. Make mediawiki.inspect depend on
  jquery.json.
* Firefox doesn't define a console.table, but doesn't throw an exception either
  if you attempt to invoke it. Use Function.prototype#call to call Firefox's
  bluff.

Change-Id: Ib45487d10488f08a98d9635ab9a2a9212e9ef69f