Add exit console command

src/main/java/com/cominatyou/console/Console.java

@@ -23,6 +23,7 @@ public class Console {
         entry("send", new Send()),
         entry("cc", new ChangeChannel()),
         entry("edit", new Edit()),
+        entry("exit", new Exit()),
         entry("clear", new Clear())
     );
 

src/main/java/com/cominatyou/console/consolecommands/Exit.java

@@ -0,0 +1,11 @@
+package com.cominatyou.console.consolecommands;
+
+import java.util.List;
+
+public class Exit implements ConsoleCommand {
+    @Override
+    public void execute(List<String> args) {
+        System.exit(0);
+    }
+
+}