Experiment: attempt to restore Travis CI

[jayaddison]

What's the problem this PR addresses?
Continuous integration via Travis seems broken at the moment; see this example build log from pull request #92.

The problem is potentially due to over-escaping of the before_script commands, based on the observed output:

The command "yarn add -D webpack@$WEBPACK_VERSION" failed and exited with 1 during .

Before opening and/or merging further changes it'd be good to get tests green again.

How did you fix it?
This isn't yet a confirmed fix; but the approach taken is to remove the outer double-quotes from the command specification.

[jayaddison]

Aha: the problem may was within one of the nested build output steps:

[noisy start-of-line removed] ... provides eslint@npm:6.8.0 with version 6.8.0 which doesn't satisfy ^4.9.0 requested by eslint-config-airbnb-base@npm:12.1.0

So updating and/or tuning a few of the package.json dependency references may resolve this.

[jayaddison]

NB: There are other dependency updates that could be beneficial to apply; the goal in this pull request is to get continuous integration working again first, and then dependency freshness can be applied as a subsequent set of changes.

[jayaddison]

Nope, it's been a long day. The eslint messages are warnings, not errors. The error line appears to be:

fsevents@patch:fsevents@npm%3A2.3.2#builtin<compat/fsevents>::version=2.3.2&hash=127e8e: Cannot apply hunk #1 (set enableInlineHunks for details)

This has been resolved in another codebase by upgrading the Yarn version registreerocks/registree-core#370 . In the builds for this repository we are dependent on the underlying OS environment.

Can/should we upgrade the Yarn version within the CI container, either by selecting a more up-to-date environment, or by performing a runtime upgrade?

[jayaddison]

cc @larixer

[larixer]

Looks good to me, thank you!