Connections now use two separate threads for writing and listening

- this should avoid dead locks, specifically when connecting to Jabit :/
- also, Java 8 features are now allowed in modules not needed by Android clients

demo/src/main/java/ch/dissem/bitmessage/demo/Application.java

@@ -52,7 +52,7 @@ public class Application {
                 .messageRepo(new JdbcMessageRepository(jdbcConfig))
                 .networkHandler(new DefaultNetworkHandler())
                 .security(new BouncySecurity())
-//                .port(48444)
+                .port(48444)
                 .listener(new BitmessageContext.Listener() {
                     @Override
                     public void receive(Plaintext plaintext) {