Upgrade to Refill v8 with theme variants for labels

[nvkelso]

With version 8 of Refill we're updating refill-style but not updating refill-style-more-labels or refill-style-no-labels.

Instead Mapzen.js will need to manually import those via the new label themes.

• Blog post: https://mapzen.com/blog/refill-levels-of-detail-and-labels/
• Documentation
  • https://mapzen.com/documentation/cartography/themes/#label
  • https://mapzen.com/documentation/cartography/themes/#detail

[nvkelso]

It may be possible to list a larger array here to accomplish this:

https://github.com/mapzen/mapzen.js/blob/ff3466315d9b0bf256e5a9b6b9202f22e5fb0a95/src/js/components/basemapStyles.js#L10-L11

  RefillMoreLabels: 'https://mapzen.com/carto/refill-style-more-labels/7/refill-style-more-labels.zip',
  RefillNoLabels: 'https://mapzen.com/carto/refill-style-no-labels/7/refill-style-no-labels.zip',

to (unverified):

  RefillMoreLabels: [ 'https://mapzen.com/carto/refill-style/8/refill-style.zip', 'https://mapzen.com/carto/refill-style/8/themes/label-10.zip' ],
  RefillNoLabels:   [ 'https://mapzen.com/carto/refill-style/8/refill-style.zip', 'https://mapzen.com/carto/refill-style/8/themes/label-0.zip' ],