Added JsonEncodeOptimizer and JsonDecodeOptimizer. Use PHP internal php_...

Hi,

I have Added JsonEncodeOptimizer and JsonDecodeOptimizer.
It use PHP internal php_json_encode/php_json_decode implements not userland function calls.

JsonEncodeOptimizer/JsonDecodeOptimizer compatible with php userland's `json_encode` and `json_decode`

It support optional return , and optional parameters ...

ex:

    let str = json_encode(obj) ;  or
    let str = json_encode(obj, JSON_HEX_QUOT) ; 

    let obj = json_decode(str) ;  or
    let obj = json_decode(str, true) ; // into  associative arrays. 


Signed-off-by: Rack Lin <racklin@gmail.com>