Bundle SASS

[adamf321]

Patternlab should bundle up SASS files for custom components and it's own components, in the same way it does for JS. We can add some options to patterns.json to make it configurable, eg include the custom SASS or not, include the default SASS or not.

[mitogh]

I think is easier if we have the two options since mainly on development is easier to just import a sass file instead of a CSS also makes more easier to reuse or overwrite.

Example: https://github.com/moxie-lean/ng-web-app/blob/956d0fd4aa9f4088659e5b4bcbadbfd786a64882/app/style.scss#L11-L15