New Macaw to Publisher features

New:

- Breaking change for Macaw: rename `sections` to `body` and `views` to `page`
- More directive classes: `only-ifnot` and `bind-value`
- Option to allow custom filtering of exported Macaw CSS

Updates:

- Option to strip directive classes from Macaw HTML
- Rewrite <img> link in exported Macaw HTML on same domain, start with `/`
- Rewrite links in exported Macaw CSS if on same domain, start with `/`
- swatches.less comments

Fixes:

- Skip undefined folders without throwing exception
- Concatenator: Trim white space from every matched asset URL