Update app to latest Node version

[c4lliope]

This change includes several different commits;
walk through the commits individually for details on changes.

There is no net functional change in the app;
instead, this change improves the overal robustness of the app
and speeds up the developer feedback loop with automatic reloading.

[c4lliope]

Demos that:

1. Functionality remains unchanged

2. Development experience is improved

[c4lliope]

@pmanko Can you run through the following test script on your computer for me?

type node
type yarn
node -v
yarn -v

# in your local copy of the `tb-mobile-app` repo
git checkout uptodate

# This might break if your node version < 10
yarn
yarn start

A browser page should open for you.
If you make a change to src/App.js,
you should see the change appear in the UI.

Now, to test that it works properly in Docker: (Make sure to replace the paths!)

cd ~/path_to/tb-api

git fetch
git checkout client-dev
git pull
echo "COMPOSE_FILE=docker-compose.yml:docker-compose.dev.yml" >> .env
echo "TB_MOBILE_CONTEXT=~/path_to/tb-mobile-app" >> .env
docker-compose up -d

Click around the app, make sure everything works.

If you change src/App.js again, you should see the page pick up the changes.

Let me know how it looks! Thanks.

[ivan-c]

Works just as expected, except text and icons "vibrate" when browser window is resized vertically on login screen or when clicking buttons on /info.

Not sure if that's the new intended behavior, but don't bother to change if too difficult or would be easier to address in follow-up PR

[ivan-c]

Are the tests passing? How is the test suite started? (thinking about setting up some CI)

[c4lliope]

As far as I can tell, all the tests are failing.

I haven't looked at the test cases much, but I'd like to get them running again.
I'll take a look when I start moving the logout button.

You should be able to run yarn test; you'll get an interactive command-line test runner.

Any preferences for a CI platform? I can start setting that up.

[ivan-c]

Thanks for the explanation, glad to hear you have a rough plan to get tests working again.

Any preferences for a CI platform? I can start setting that up.

I have the most experience with TravisCI, and found it pretty flexible (root access and docker support and great free plan for FOSS), but I'm not attached if there's something you're more comfortable with.

[ivan-c]

Wanted to note I saw this warning when building the front-end docker image:

(node:8) [DEP0005] DeprecationWarning: Buffer() is deprecated due to security and usability issues. Please use the Buffer.alloc(), Buffer.allocUnsafe(), or Buffer.from() methods instead.

[c4lliope]

(node:8) [DEP0005] DeprecationWarning: Buffer() is deprecated due to security and usability issues. Please use the Buffer.alloc(), Buffer.allocUnsafe(), or Buffer.from() methods instead.

Ah right, I saw that too.
It looks like this is coming from yarn, and was fixed in a more recent version.

I'll see if I can upgrade our yarn version.