added jar task to build.gradle

Server/build.gradle

@@ -14,6 +14,20 @@ test {
     maxParallelForks = 1
 }
 
+var mainClassName = "uulm.teamname.marvelous.server.Server"
+
+jar {
+    manifest {
+        attributes "Main-Class": "$mainClassName"
+    }
+
+    from {
+        configurations.runtimeClasspath.collect {it.isDirectory() ? it : zipTree(it) }
+    }
+
+    duplicatesStrategy = DuplicatesStrategy.EXCLUDE
+}
+
 dependencies {
     implementation project(':Gamelib')