Attach `.beta` so we default to Sprockets 4 unless you explicit 3.x.
Attach `.beta` so we default to Sprockets 4 unless you explicit 3.x.

jekyll/jekyll-assets,jeremy/jekyll-assets,mattbeedle/jekyll-assets,jekyll/jekyll-assets,mattbeedle/jekyll-assets,jekyll-assets/jekyll-assets,jekyll/jekyll-assets,jeremy/jekyll-assets,mattbeedle/jekyll-assets,jeremy/jekyll-assets,jeremy/jekyll-assets,jekyll-assets/jekyll-assets,jekyll/jekyll-assets,jekyll-assets/jekyll-assets,mattbeedle/jekyll-assets