Merge pull request #8 from sharelatex/bg-upgrade-to-node-6x

upgrade to node 6.9.5

services/document-updater/.nvmrc

@@ -1 +1 @@
-4.2.1
+6.9.5

services/document-updater/Jenkinsfile

@@ -11,7 +11,7 @@ pipeline {
     stage('Install') {
       agent {
         docker {
-          image 'node:4.2.1'
+          image 'node:6.9.5'
           args "-v /var/lib/jenkins/.npm:/tmp/.npm -e HOME=/tmp"
           reuseNode true
         }
@@ -28,7 +28,7 @@ pipeline {
     stage('Compile and Test') {
       agent {
         docker {
-          image 'node:4.2.1'
+          image 'node:6.9.5'
           reuseNode true
         }
       }