added javadoc generation to build file

WordPressUtils/build.gradle

@@ -87,3 +87,17 @@ uploadArchives {
         }
     }
 }
+
+android.libraryVariants.all { variant ->
+
+    task("generate${variant.name}Javadoc", type: Javadoc) {
+        description "Generates Javadoc for $variant.name."
+        source = variant.javaCompile.source
+        classpath = files(variant.javaCompile.classpath.files, android.getBootClasspath())
+
+        options {
+            links "http://docs.oracle.com/javase/7/docs/api/"
+        }
+        exclude '**/R.java'
+    }
+}