fix syntax (#74)

Signed-off-by: Olivier Lamy <olamy@apache.org>

Jenkinsfile

                                 // -Dmaven.compiler.fork=true: Do compile in a separate forked process
                                 // -Dmaven.test.failure.ignore=true: Do not stop, if some tests fail
                                 // -Pci-build: Profile for CI-Server
-                                sh "mvn ${cmdLine} -B -U -e -fae -Dorg.slf4j.simpleLogger.showThreadName=true -Pci-build -T${THREADS}"
+                                sh "mvn ${cmdLine} -B -U -e -fae -Dorg.slf4j.simpleLogger.showThreadName=true -Pci-build -T${params.THREADS}"
                             }
                 }
             }
                                         {
                                             sh "chmod 755 ./src/ci/scripts/prepareWorkspace.sh"
                                             sh "./src/ci/scripts/prepareWorkspace.sh"
-                                            sh "mvn clean install -U -B -e -fae -Dorg.slf4j.simpleLogger.showThreadName=true -Pci-build -T${THREADS}"
+                                            sh "mvn clean install -U -B -e -fae -Dorg.slf4j.simpleLogger.showThreadName=true -Pci-build -T${params.THREADS}"
                                         }
                             }
                         }