Re restore

Based on #10. Can now restore a piece of content. The revision fields and last modified timestamps are updated automatically.

A caveat is that you may find yourself having to modify the required fields in Composer to be able to publish the content again.

The API URL is still hardcoded. Let's have a chat about how to solve that in a way we're happy with.
As far as I'm concerned a URL is not a secret and can happily be committed. In fact I'd encourage it, as the alternative is unnecessary obscurity and faff for developers.