refactor(ci): redo pipeline

reworked pipeline to suit all branches

This pulls, builds and publishes now for every branch on the repo
Tag used is the branch name

if the commit the pipeline runs matches the format [0-9]+.[0-9]+.[0-9]+
the release stage is run additionally, which pushs the built image
additionally with the tags 'latest' and the tag.

On Jenkins the old Pipeline configurations are disabled and replaced by
a multibranch pipeline configuration

Jenkinsfile

+
+def version = ""
+
 pipeline {
+
     environment {
         registry = "hftstuttgart/modocot-backend"
         registryCredential = 'Dockerhub'
         dockerImage = ''
     }
+
     agent any
+
     tools {
         jdk 'Java11'
         maven 'Maven_Home'
     }
+
     stages {
-        stage('Checkout') {
+        stage('prepare') {
             steps {
-                echo 'Checkout Repository..'
-                git branch: 'master',
-                url: 'https://transfer.hft-stuttgart.de/gitlab/HFTSoftwareProject/MoDoCoT-Backend.git'
+                checkout ([
+                    $class: 'GitSCM',
+                    branches: scm.branches,
+                    extensions: scm.extensions + [[$class: 'CloneOption', noTags: false, reference: '', shallow: false]],
+                    userRemoteConfigs: scm.userRemoteConfigs
+                ])
+                script {
+                    version = sh(script: 'git describe --tags --always', returnStdout: true).trim()
+                    echo sh(script: 'env|sort', returnStdout: true)
+                }
+
             }
         }
-        stage('Build') {
+
+        stage('compile') {
             steps {
-                echo 'Maven Build..'
-                sh 'mvn clean package -DskipTests=false'
+                sh 'mvn clean package'
             }
         }
-        stage('Docker Build..') {
-            steps{
+
+        stage('build Docker image') {
+            steps {
                 script {
-                    dockerImage = docker.build registry + ":latest"
+                    dockerImage = docker.build registry
                 }
             }
         }
-        stage('Push to Dockerhub..') {
-                    steps{
-                        script {
-                            docker.withRegistry( '', registryCredential ) {
-                                dockerImage.push()
-                            }
-                        }
+
+        stage('push development image') {
+            steps {
+                script {
+                    docker.withRegistry( '', registryCredential ) {
+                        dockerImage.push("${env.GIT_BRANCH}")
                     }
                 }
+            }
+        }
 
-        stage('ShellScript') {
+        stage('release') {
+            when {
+                expression { version ==~ /[0-9]+.[0-9]+.[0-9]+/ }
+            }
             steps {
-                echo 'Exectue Shellscript..'
-                sh 'chmod 744 restart_modocot_backend.sh && ./restart_modocot_backend.sh'
+                script {
+                    docker.withRegistry( '', registryCredential ) {
+                        dockerImage.push("latest")
+                        dockerImage.push("${version}")
+                    }
+                }
             }
         }
     }