Changes to make the Gradle work

- commented `java() {...}` within build.gradle
- added following files
   1. gradlew
   2. gradlew.bat (for windows)
   3. gradle/wrapper/gradle-wrapper.properties (for ./gradlew command execution)
   4. gradle/wrapper/gradle-wrapper.jar (for ./gradlew command execution)

build.gradle

@@ -40,10 +40,10 @@ sourceCompatibility = '1.7'
 configurations.all {
 }
 
-java {
-    withSourcesJar()
-    withJavadocJar()
-}
+//java {
+    //withSourcesJar()
+    //withJavadocJar()
+//}
 
 publishing {
     publications {