jupyterhub: install ijavascript kernel

jupyterhub/tasks/ijavascript.yml

+# Jessie-backports contains a recent version of nodejs… But without any npm…
+# The nodesource version contains a npm binary
+# Not that it seems not required for Debian stretch
+- name: Install npm deps
+  npm:
+    name: ijavascript
+    global: yes

jupyterhub/tasks/main.yml

@@ -87,4 +87,7 @@
     - restart jupyterhub
 
 - name: jupyterhub is started
-  service: name=jupyterhub state=started
\ No newline at end of file
+  service: name=jupyterhub state=started
+
+- name: Install ijavascript notebook kernel
+  include: ijavascript.yml