Drop Node v4 support

[bravo-kernel]

It seems adding tailwind has bumped the required node version to 6.9.0 or higher whereas the previous builds ran ran perfectly against node 4, using the Ember recommended addon settings :

# we recommend testing addons with the same minimum supported node version as Ember CLI
# so that your addon works for all apps
- "4"

Error from Travis:

error tailwindcss@0.4.3: The engine "node" is incompatible with this module. Expected version ">=6.9.0"

Build details at https://travis-ci.org/alt3/ember-light-table-cell-type-link/jobs/359024220

[dfreeman]

It looks like punycode (via ember-cli-tailwind's jsdom dep) introduces an incompatibility as well. Node 4 is EOL as of April 30, and I know ember-cli-addon-docs-esdoc already has its minimum set at 6, but so far we'd managed to avoid that in the core.

@samselikoff @pzuraq Thoughts? It seems like our options are likely:

• Go ahead and jump ship on node 4, and by extension maybe be a catalyst for other addons starting to do so ahead of schedule and in contradiction to the official recommendations of the CLI team
• Hold off on Tailwind (😢) or try to see about lowering the engine requirement there (that change itself doesn't seem to have been tied to wanting a particular language feature in Node 6, but it may also be a hard argument to make for a version that's dying in a month anyway)

[samselikoff]

Ya prob not worth it for a version dying in a month.

We could enable ember-cli-tailwind during dev then shut it off, and copy+paste the generated tailwind.css file and just app.import it? Eventually I want to use the dev-time build functionality of ember-cli-tailwind to pare down our styles + colors, but for now we can just ship a static build.

[dfreeman]

Even that might be more trouble than it's worth, unless you're just itching to make that change 🙂

Maybe we're just the Problem Child for the next 33 days and then we let the issue solve itself?

[bravo-kernel]

As an end-user I had no idea Node was this close to EOL but looking at https://github.com/nodejs/Release putting any effort into version 4 makes no sense to me.

I do think this repo should clearly state/promote that we follow the Ember support cycle. Maybe we can add a Requirements note to the Usage page stating something similar to:

Addon Docs follows the support cycle of Ember and support. For supported versions see...

Please let me know if this is welcomed, otherwise feel free to close this ticket.

[pzuraq]

I'm inclined to agree here, Node v4 is going to be dropped very, very soon and this package isn't even technically v1.0.0 yet. I think setting the bar at v6 is reasonable, if anything it'll encourage people to upgrade sooner, which should help get as many addons updated as soon as possible

We should keep this issue open until we drop support for v4 in package.json explicitly.