Joël Quenneville authored Apr 19, 2017 and Eugen Rochko committed Apr 19, 2017

Previously the `bin/setup` script only installed the Ruby dependencies
via Bundler. This is not sufficient to get the test suite to pass. We
also need the JavaScript dependencies.

This commit installs the JavaScript dependencies as part of the
`bin/setup` script via Yarn.

This allows for a successful

    bin/setup && bundle exec rake

on a fresh clone of the repo.