Merge pull request #6 from sharelatex/sk-node-6

Change to Node 6

services/contacts/.nvmrc

@@ -1 +1 @@
-4.2.1
+6.14.1

services/contacts/Jenkinsfile

@@ -2,7 +2,7 @@ pipeline {
   
   agent {
     docker {
-      image 'node:4.2.1'
+      image 'node:6.14.1'
       args "-v /var/lib/jenkins/.npm:/tmp/.npm"
     }
   }