update publishing scripts

publish.gradle

@@ -1,4 +1,5 @@
 apply plugin: 'maven-publish'
+apply plugin: 'signing'
 
 task javadocsJar(type: Jar) {
     classifier = 'javadoc'
@@ -58,3 +59,8 @@ publishing {
         
     }
 }
+
+signing {
+    useGpgCmd()
+    publishing.publications.forEach { sign it }
+}