Officially migrate to newer version of NodeJS

[grtjn]

Running installation for NodeJS 0.10 (what you get automatically on RHEL and CentOS 6/7) has started showing:

================================================================================

                       NODE.JS v0.10 DEPRECATION WARNING                      
  Node.js v0.10 will cease to be actively supported in October 2016.

  This means you will not continue to receive security or critical stability
  updates for this version of Node.js beyond that time.

  You should begin migration to a newer version of Node.js as soon as
  possible. Use the installation script that corresponds to the version of
  Node.js you wish to install. e.g.

   * https://rpm.nodesource.com/setup_4.x — Node.js v4 LTS "Argon" (recommended)
   * https://rpm.nodesource.com/setup_6.x — Node.js v6 Current

  Please see https://github.com/nodejs/LTS/ for details about which version
  may be appropriate for you.

  The NodeSource Node.js Linux distributions GitHub repository contains
  information about which versions of Node.js and which Linux distributions
  are supported and how to use the install scripts.
    https://github.com/nodesource/distributions
================================================================================

[grtjn]

I think this project runs pretty smooth on more recent NodeJS, but worth another check, and we could/should upgrade dependencies too. We may also need to consider actually upgrading NodeJS on servers..

[Audarth]

Would we upgrade to 4.6.1 which is currently stable and only getting security updates or 6.9.1 which was bleeding edge but is going into long term support at the moment?

https://github.com/nodejs/LTS#lts-schedule

[grtjn]

Maintenance for v0.12 ends by the end of this year, so yeah, v4 is wisest..

[grtjn]

By this time 6 is LTS, and newest demo servers are bootstrapped with this version too: https://github.com/grtjn/mlvagrant/blob/master/project/project.properties#L129

I think we can move forward with this..

[grtjn]

Too many dependencies started to malfunction because of old node, so upgraded CI server, which allowed safely upgrading minimum node engine requirement. No further changes for now, though we likely want to get rid of a few of the deprecation warnings soon.