Allow overriding default webpack dev server options

[jure]

There is currently no way to override webpack dev server options. For example, we specifically want the dev server to look at node_modules/ too (to develop using linked dependencies) and there isn't a way to do that.

[sapegin]

Thanks, make sense!

Probably we should still force contentBase.

[codecov-io]

Codecov Report

Merging #690 into master will not change coverage.
The diff coverage is 100%.

Impacted Files	Coverage Δ
scripts/create-server.js	92.3% <100%> (ø)	⬆️

[jure]

@sapegin I had a solution where I'd just play with the order of things in the merge(), but this seems more readable and explicit.

[sapegin]

I’d actually add it to merge as the last argument — would be more readable and consistent.

[jure]

Yeah, that's what I had, personally found the override a bit too implicit then. I'll do it, though, sure.

[sapegin]

Thanks, merged!