This refactor removes duplicated logic for deciding whom the messages get sent to.
It also normalizes behavior ensuring that all CCed addresses are sent to in all cases that CCed individuals should be notified.
We accomplish this by attching files to out-bound mail diffrently
depending on the versino of Python in effect. In Py2 we can read
the files ourseles and the standard library will still
be able to use the text we pass as if it were bytes. Under Py3,
however, email.message will complain if it doesn't get to decode
the bytes itself, so instead of attaching the contents directly
we just pass the path to the file as a string instead. Unfortunately,
Django 1.8 does not work with this Python 3 approach, due to its
not yet having reverted to the newly improved standard library's
mail-message implementation, and thus requiring us to know more
about the character-encoding/mimetype of the attachment than I've
been able to gather cleanly by this point.
Extract attachment processing from forms, views.staff, and management.command.get_email modules, and consolidate it into a unified lib module function.
Also refactor the affected components, most notably lib.send_templated_email, to make it easier (IMO) to reason about changes to them.
Add unit tests for attachments with UTF-8 filenames, and functional tests for submission of same, as well as ASCII versions, through the public ticket-form.
Remove unused Attachment method "get_upload_to".
- use of patterns() in urls.py is deprecated
- render() functions accept only dicts - introduced checks to ensure downward compatibility back to Django 1.7
