[release] 4.2.1
[release] 4.2.1

Change-Id: Ic078c123ccb2a6fa8553c78c2ff73a5682bc66df

shelsonjava/kurento-jsonrpc-js,shelsonjava/kurento-jsonrpc-js,KurentoLegacy/kws-rpc-builder,Kurento/kurento-jsonrpc-js,Kurento/kurento-jsonrpc-js,Kurento/kurento-jsonrpc-js