As mentioned in commits 5311daadf and bb958daf0, using links combined
with JavaScript to generate POST (or, in this case, DELETE) requests to
the server has a few issues.
By default, Rails disables submit inputs (<input type="submit">) when
they're pressed so we avoid a double-submission when users click the
button twice.
However, Rails does not disable submit buttons (<button type="submit">)
when they're pressed. This means there's a chance users might press the
button several times. Even if most our table actions are idempotent, it
might cause certain issues. For instance, pressing the "Delete" button
twice means the second request might raise an
`ActiveRecord::RecordNotFound` exception.
Disabling the button also gives feedback to users, letting them know
they've correctly clicked the button.
