Don't try to build MQTT V5 in this branch

Author: Ian Craggs

.travis.yml

@@ -21,7 +21,6 @@ before_install:
 script:
   - mvn -B clean -q
   - mvn -B --projects org.eclipse.paho.client.mqttv3,org.eclipse.paho.client.mqttv3.test test -q
-  - mvn -B --projects org.eclipse.paho.mqttv5.common,org.eclipse.paho.mqttv5.client,org.eclipse.paho.mqttv5.client.test test -q
 
 #addons:
 #  apt: