Added WriteProxy with creation method in Client, added caches to LocalDb

src/main/java/envoy/client/net/Client.java

@@ -118,6 +118,17 @@ public class Client implements Closeable {
 		return cache;
 	}
 
+	/**
+	 * Creates a new write proxy that uses this client to communicate with the
+	 * server.
+	 *
+	 * @param localDb the local database that the write proxy will use to access
+	 *                caches
+	 * @return a new write proxy
+	 * @since Envoy Client v0.3-alpha
+	 */
+	public WriteProxy createWriteProxy(LocalDb localDb) { return new WriteProxy(this, localDb); }
+
 	/**
 	 * Sends a message to the server. The message's status will be incremented once
 	 * it was delivered successfully.