Install node with npm ci

[Jonathan Yee]

Since node 5.7, they have introduce npm ci which installs from package-lock instead of upgrading on semver.

This would maintain the CI's version and speed up build time.

[Landon Abney]

Atom packages are installed using apm, not npm. The CI environment uses apm to install modules to match the environment that users will be using to install the package.

You can look through the atom/apm repository for further insights about getting the npm version it uses behind the scenes updated, as currently it doesn't actually understand package-lock.json files in the first place.

Thanks for taking the time to file an issue!