Add support for generating global javadoc.

build.gradle

 
 apply from: 'clover.gradle'
 apply from: 'local-dependency-change.gradle'
+apply from: 'javadoc.gradle'
 
 task createWrapper(type: Wrapper) {
     description 'Downloads and installs an up-to-date wrapper for gradle.'

javadoc.gradle

+apply plugin: 'java'
+
+gradle.projectsEvaluated {
+    task aggregateJavadoc(type: Javadoc) {
+        source allprojects.collect { it.sourceSets.main.allJava }
+        classpath = files(allprojects.collect { it.sourceSets.main.compileClasspath })
+        destinationDir = file("${buildDir}/docs/javadoc")
+
+        println source.asPath
+    }
+}
+