removed json,xml, wso2event and keyvalue mappers from build
removed json,xml, wso2event and keyvalue mappers from build

ksdperera/siddhi,suhothayan/siddhi,wso2/siddhi,sajithshn/siddhi,miyurud/siddhi,ksdperera/siddhi,grainier/siddhi,ChariniNana/siddhi,dilini-muthumala/siddhi,ChariniNana/siddhi,gokul/siddhi,ramindu90/siddhi,mohanvive/siddhi,codemogroup/siddhi,slgobinath/siddhi,mohanvive/siddhi,slgobinath/siddhi,codemogroup/siddhi,nadundesilva/siddhi,nadundesilva/siddhi,gokul/siddhi,minudika/siddhi,grainier/siddhi,dilini-muthumala/siddhi,ramindu90/siddhi,lgobinath/siddhi,tishan89/siddhi,lgobinath/siddhi,suhothayan/siddhi,minudika/siddhi,tishan89/siddhi,wso2/siddhi,miyurud/siddhi,sajithshn/siddhi