* Change Sender definition (remove old Message from API) and update
any existing calls through that API
* Rewrite SMTPSender to use provider messages
* Add attachments to RFC822Output
* Minor bugfixes in RFC822Output
* Unit tests
errors, inconsistencies in passing Application/Activity/Context, and
some error handling cleanups. These are all changes that would have
probably been made before the original submits, but I didn't want
to fix them in the integration step.
Original author: stadler
Automated import of CL 144522
