fix for ESBJAVA-3290

fix for the "issue Unable to create POST request against REST endpoint where body parameter name starts with digit" reported in [1] 

added a new formatter which will drop the  "_JsonReader_PD_" and "_JsonReader_PS" Strings from out message


ex: 
 "2a" "_JsonReader_PD_2a" replace with ""
"$a" "_JsonReader_PS_a" replace with "$" 

https://wso2.org/jira/browse/ESBJAVA-3290