start connection manager, fix some issues

core/src/main/groovy/com/muwire/core/Core.groovy

@@ -88,6 +88,7 @@ class Core {
 			new LeafConnectionManager(eventBus,3, hostCache) : new UltrapeerConnectionManager(eventBus, 512, 512, hostCache)
 		eventBus.register(TrustEvent.class, connectionManager)
 		eventBus.register(ConnectionEvent.class, connectionManager)
+		connectionManager.start()
 		
 		log.info("initializing cache client")
 		CacheClient cacheClient = new CacheClient(eventBus,hostCache, connectionManager, i2pSession, props, 10000)

core/src/main/groovy/com/muwire/core/connection/ConnectionManager.groovy

@@ -53,7 +53,7 @@ abstract class ConnectionManager {
 	
 	abstract void onConnectionEvent(ConnectionEvent e)
 	
-	private void sendPings() {
+	protected void sendPings() {
 		final long now = System.currentTimeMillis()
 		getConnections().each { 
 			if (now - it.lastPingSentTime > PING_TIME)

core/src/main/groovy/com/muwire/core/connection/PeerConnection.groovy

@@ -63,7 +63,7 @@ class PeerConnection extends Connection {
 		byte [] payload
 		if (message instanceof Map) {
 			payload = JsonOutput.toJson(message)
-			DataUtil.packHeader(payload.bytes.length, writeHeader)
+			DataUtil.packHeader(payload.length, writeHeader)
 			writeHeader[0] &= 0x7F
 		} else {
 			// TODO: write binary