added building standalone

.gitignore

@@ -1,2 +1,3 @@
 /.gradle/
 /bin/
+/build/

build.gradle

@@ -18,7 +18,7 @@ dependencies {
 }
 
 application {
-    mainClass = 'Main'
+    mainClass = 'de.jottyfan.guitools.Main'
 }
 
 test {
@@ -28,11 +28,12 @@ test {
 jar {
     manifest {
         attributes (
-            'Main-Class': 'Main',
+            'Main-Class': application.mainClass,
             'Implementation-Version': version
         )
     }
     archiveBaseName = project.name
+    archiveVersion = project.version
     from {
         configurations.runtimeClasspath.collect { it.isDirectory() ? it : zipTree(it) }
     }