Raise new MandrillRecipientsRefused exception
when Mandrill returns 'reject' or 'invalid' status
for *all* recipients of a message.
(Similar to Django's SMTP email backend raising
SMTPRecipientsRefused.)
Add setting MANDRILL_IGNORE_RECIPIENT_STATUS
to override the new exception.
Trap JSON parsing errors in Mandrill API response,
and raise MandrillAPIError for them. (Helps with #93.)
Closes#80.
Closes#81.
Rapid-fire pelting from our Travis tests sometimes
causes the Mandrill API to queue a "send" call, rather
than deal with it immediately. If that occurs, we
generally have to just ignore that test (in that test run).
