Migrate everything on Gradle

Also added tasks to run the server & client separately

ChatApp/app/src/main/java/ChatApp.java

@@ -0,0 +1,21 @@
+import java.net.InetSocketAddress;
+
+import client.ClientConsole;
+import server.Server;
+
+public class ChatApp {
+    public static void main(String[] args) throws Exception {
+        Server server = new Server(6665);
+        ClientConsole client = new ClientConsole(new InetSocketAddress("localhost", 6665));
+
+        client.getClientInterface().SendCreateRoom("101");
+
+        client.joinThread();
+
+        System.out.println("Stopping server ...");
+
+        server.close();
+
+        System.out.println("Done !");
+    }
+}