Attach source JARs without forking to fix Jenkins warnings (#741)

This fixes the following warnings on Jenkins builds:

[WARNING] Failed to getClass for org.apache.maven.plugins.source.SourceJarMojo

See also: https://issues.jenkins-ci.org/browse/JENKINS-27372

Signed-off-by: Wouter Born <github@maindrain.net>

bundles/pom.xml

@@ -251,7 +251,7 @@
           <execution>
             <id>attach-sources</id>
             <goals>
-              <goal>jar</goal>
+              <goal>jar-no-fork</goal>
             </goals>
           </execution>
         </executions>