This change, which is not properly documented nor tests present, adds
support for making sure those who don't want emails from us do not
receive them.
I believe I've caught most of the places we want this change supported.
Requests can now be placed "on hold", and getRequest() can ignore held
requests.
This required addition of a table, and another API call holdRequest().
Tests were not written here, which was a mistake. Unit tests and docs
are needed. A FIXME was added, at least.
Also, minor imporvements to reporting on fulfilled requests.
