Fix discrepancy with the way jQuery does $.param(). Issue 850

Old behaviour for $.param() misses out indexes for arrays which have objects within them whereas jQuery (1.4 and 1.latest tested) will add them in this situation.

I have:

 1. Updated code so it creates data which is the same as what jQuery would produce.
 2. Updated AJAX test "testParamComplex" so it tests for data that jQuery would actually produce (the test was wrong).
 3. Added a new test which for the un-jQuery-like / incompatible node-querystring (Express) which was discovered in issue 850.

AJAX Tests still passing (in browsers)