Jenkinsfile: Try yet another syntax..

Jenkinsfile

@@ -9,8 +9,8 @@ node {
          stage 'test'
          sh 'env'
          sh 'curl https://glide.sh/get | sh'
-         sh "mv ${env.GOPATH}/src/github.com/UNINETT ${env.GOPATH}/src/github.com/uninett"
-         sh "cd ${env.GOPATH}/src/github.com/uninett/jwt-tokenissuer"
+         sh 'mv \$GOPATH/src/github.com/UNINETT \$GOPATH/src/github.com/uninett'
+         sh 'cd \$GOPATH/src/github.com/uninett/jwt-tokenissuer'
          sh 'glide install'
          sh 'make test'
 
@@ -22,7 +22,7 @@ node {
          stage 'package'
          unstash 'binary'
          sh 'mv jwt-tokenissuer /src/'
-         sh "fpm -s dir /src=/opt/jwt-tokenissuer -t deb -n jwt-tokenissuer -v ${env.VERSION_STRING}"
+         sh 'fpm -s dir /src=/opt/jwt-tokenissuer -t deb -n jwt-tokenissuer -v \$VERSION_STRING'
          archive includes: '*.deb'
      }
 }