Added MySQL container for SonarCloud tests

            steps{

                script{

                    withCredentials([usernamePassword(credentialsId: 'SonarCloud_Zegorax_Token', passwordVariable: 'SONARCLOUD_API_TOKEN', usernameVariable: 'SONARCLOUD_API_USER')]) {

                        docker.image('mysql').withRun('-e MYSQL_ROOT_PASSWORD=root -e MYSQL_DATABASE=mentorarc -e MYSQL_USER=mentorarc -e MYSQL_PASSWORD=mentorarc') { c ->

                            docker.image('mysql').inside("--link ${c.id}:db") {

                                /* Wait until mysql service is up */

                                sh 'while ! mysqladmin ping -hdb --silent; do sleep 1; done'

                            }

                            docker.image('maven:3-alpine').inside() {

                                    checkout scm

                                    sh 'mv src/main/resources/application.properties.production src/main/resources/application.properties'

                                    sh 'mvn verify sonar:sonar'

                            }

                        }

                    }

                }

            }