Run Javascript tests on default bundle exec rake
Run Javascript tests on default bundle exec rake

At the moment, Javascript tests aren't run when you run `bundle exec rake`.
They are only run when running `bundle exec rake spec:javascript`.
This can mean failing tests go unnoticed until you push to Github and the build fails on CI.

This expands the default task to include `spec:javascript`.

alphagov/static,alphagov/static,alphagov/static