Revisions should not url_encode or at least url_encode(diff("content"))

In #521 it looks like the `Revisions` table does something like this:

diff(url_encode("content"))

This makes little sense, as the diffing will always yield all of the document. And those are stored in `lastContent` and `content` anyway.

This should be reversed to be

url_encode(diff("content"))

I'm not even entirely sure why the url-encode is done in the first place, but it appears to be there.