Squashed 'vendor/assets/javascripts/d3/plugins/' changes from 37cf815..fc984ac

fc984ac Update copyright year.

git-subtree-dir: vendor/assets/javascripts/d3/plugins
git-subtree-split: fc984ac269a9522c4b12ec568839ab703b11d51e
Merge commit '88ae0e7d8f285d2f8f3a8e71e52ad2e5b75d403c'

* commit '88ae0e7d8f285d2f8f3a8e71e52ad2e5b75d403c':
  Squashed 'vendor/assets/javascripts/d3/plugins/' changes from 37cf815..fc984ac
Bump gem version