fix for ESBJAVA-3290

Dropped dependency on org.apache.axis2.builder.XFormURLEncodedBuilder()
and modified to handle invalid charaters as follows
     ex:  "2a" replace with "_JsonReader_PD_2a"
            "$a" replace with "_JsonReader_PS_a"


org.apache.axis2.transport.http.XFormURLEncodedFormatter removed to handle contentType="application/x-www-form-urlencoded"
and added org.apache.synapse.commons.formatters.XFormURLEncodedFormatter