Bump depedencies and true up implementation details.

[phyllisstein]

These changes upgrade as many of Clay CLI’s dependencies as possible without breaking sites builds. This derisks additional work to integrate Webpack into Clay’s build pipeline: we can now be more confident that Webpack and its dependencies won’t break Clay and its dependencies, and vice versa.

Clay CLI’s tests needed cosmetic changes, but otherwise continue to pass. sites builds on my local machine, and a feature-branch deployment will be up shortly. (See nymag/sites#9736.)

[mattoberle]

This looks good!
I see that the js-yaml changes align with the deprecation of the safe* API in 4.0.0.

With 26 direct dependencies all getting a major version change the additional testing on a nymag/sites feature branch definitely makes sense.

[phyllisstein]

Thanks for taking a look. I’ve got sites#clay-pack-spike pinned to this Git branch. Would it be better, to your mind, to deploy a prerelease claycli? I’m never not suspicious of Node version management.

[coveralls]

Coverage remained the same at 100.0% when pulling 52826b4 on upgrade-dependencies into f42e748 on master.