Pin nodejs to come from nodesource repo

We're installing the nodesource repo, that means we want to install
from it even if the distro happens to have a newer version.

Change-Id: Ib37615089a2b11b8cc8bdfbe811e5f9cb3d1a529

roles/install-nodejs/files/00-nodesource.pref

@@ -0,0 +1,3 @@
+Package: nodejs
+Pin: origin deb.nodesource.com
+Pin-Priority: 900

roles/install-nodejs/tasks/main.yaml

@@ -9,6 +9,12 @@
     state: present
   become: yes
 
+- name: Pin nodejs installs to nodesource
+  copy:
+    src: 00-nodesource.pref
+    dest: /etc/apt/preferences.d/00-nodesource.pref
+  become: yes
+
 - name: Add nodesource repository key
   apt_key:
     url: "https://deb.nodesource.com/gpgkey/nodesource.gpg.key"