Exclude deleted contacts when searching by Email
880c21ca removes check on deleted entities in APIWrapper
as it can cause issues related to Cases #43 (closed).
However, for Emails it's a very sensible check.
Removing checking on deleted contacts makes FindOrCreateContactByEmail
(and similar actions) return deleted contacts, so the rest of the form processor will act on them (e.g. adding contributions to deleted contacts).
This MR adds back the checking for Emails.