gradle: fix vtm-android install + generate source jars

vtm/build.gradle

@@ -15,6 +15,14 @@ sourceSets {
   main.compileClasspath += configurations.providedCompile
 }
 
+task sourcesJar(type: Jar, dependsOn: classes) {
+  classifier = 'sources'
+  from sourceSets.main.allSource
+}
+artifacts {
+  archives sourcesJar
+}
+
 eclipse.classpath {
   //you can tweak the classpath of the Eclipse project by adding extra configurations:
   plusConfigurations += [ configurations.providedCompile ]