Stop ignoring task results

This is essentially a revert of 9cbff312a. The commit was at the advice
of the Celery docs for optimization, but I've since decided that the
downsides in terms of making things harder to debug (it makes Flower
nearly useless, for instance) are bigger than the upsides in performance
gain (which seem extremely small in practice, given how long our tasks
take, and the number of tasks we have).

bookwyrm/emailing.py

@@ -75,7 +75,7 @@ def format_email(email_name, data):
     return (subject, html_content, text_content)
 
 
-@app.task(queue=HIGH, ignore_result=True)
+@app.task(queue=HIGH)
 def send_email(recipient, subject, html_content, text_content):
     """use a task to send the email"""
     email = EmailMultiAlternatives(