RESTful routing for admin censor rule actions
Refactor shared setup to filter
Refactor - group common logic branches
Don't raise internal error when handling non-user or request rules

Handle attempts to edit or destroy global or public body censor rules
with a notice and a redirect.

Closes #2009
Make sure raw_email is initialised with some data.

This is to make sure that the file that is used to store the data is
created and written to before any attempt to read from it.