External css

[hewIngram]

This addresses use of external css files for components as described here: #76

@eddyerburgh not sure how you feel about just writing the external file into stylePart but it seemed like the easiest way of doing this.

[eddyerburgh]

Looks good :)

It's fine to rewrite the content, that's how we do it for script and template.

One small refactor—can you use the loadSrc function. You could move it into lib/utils to use it in both files.

[hewIngram]

Ah I totally didn't spot that. 👍
I also renamed filename to filepath as it is the path + more consistent with the rest of the code.

The utils.js file doesn't have unit tests, do you want me to write some or are you happy with the e2e coverage?

[eddyerburgh]

Nice job, thanks for this :)

[eddyerburgh]

The e2e tests are fine