Add Jenkinsfile for Pipeline

Jenkinsfile

+node{
+    stage('SCM Checkout'){
+        git 'https://lab.it.hs-hannover.de/htf-cmh/vis_buildserver_gitlabci_demo'
+    }
+    
+    stage('Compile-Package'){
+        sh 'mvn package'
+    }
+}
\ No newline at end of file