Update maven plugin version and enable mqttv3 tests

Author: rdasgupt

pom.xml

@@ -115,7 +115,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-compiler-plugin</artifactId>
-                    <version>2.7.1</version>
+                    <version>3.8.1</version>
                     <configuration>
                         <encoding>${project.build.sourceEncoding}</encoding>
                         <source>${java.version}</source>
@@ -355,6 +355,7 @@
     <modules>
         <module>org.eclipse.paho.client.mqttv3</module>
         <module>org.eclipse.paho.client.mqttv3.repository</module>
+        <module>org.eclipse.paho.client.mqttv3.test</module>
         <module>org.eclipse.paho.mqttv5.client</module>
         <module>org.eclipse.paho.mqttv5.client.repository</module>
     </modules>