Rerun sass task in prod mode for CI

[rpowis]

Problem

After the refactoring of gulp tasks, the sass job doesn't build the production stylesheets during the build job.

Because the sass task is being run as a dependency of the test task, the global.runmode is set as the default dev. Due to this, the sass task doesn't minify the styles or put them in the assets/dist directory ready to be zipped and deployed.

Example Screenshot

Solution

By explicitly calling the sass task as a step in the build task it picks up the global.runmode = 'prod' setting and builds the styles for production.

Example Screenshot

Caveats

The sass task is being run twice as it's still a dependency of the test task. Ideally, the sass task would only be run once and then a separate minification step would be run for production.

That hasn't been done for this change as we need to get a fix out for missing styles quickly and introducing a new minification library could produce different output to the original sass job.