This will stop us repeatedly forgetting to add `novalidate` and
`autocomplete='off'` to our forms (which is how most of them are set
up).
It uses sensible defaults, based on how we most-commonly configure
forms:
- most of our forms are `post`ed (but this can be overridden)
- `autocomplete` should only be enabled where it makes sense, otherwise
it’s more annoying than useful (but this can be overriden)
- we should never be using HTML5 form validation because our own error
styles and messages are better
For both SMS senders and email reply to addresses this commit adds:
- a delete link
- a confirmation loop
It doesn’t let users delete:
- default SMS senders or reply to addresses (they always have to have
one)
- inbound numbers
It assumes that the API will allow updating of an attribute named
`active` on the respective database rows. It could work in a different
way. We can’t do complete deletion though because these will still be
keyed to notifications.
