In #1618, we removed the explicit include of jquery_ujs as it should
no longer be necessary. Alas, this broke the ability to destroy items.
This wasn't caught by the tests because Capybara tries to be clever with
these links, sending the DELETE directly instead of clicking on the link. We
disable this here and switch the specs to use the JS driver so that
we're actually testing the functionality (it can't pass without).
Adding the include of jquery_ujs solves this for now, unblocking us
from having a release for lots of other features and allows us to
revisit this problem again (in a way that we'll catch it this time!).
Fixes #1643 (closed).