robustify Differential and Maniphest mailhandlers wrt attachments
Summary:
a few things
- make the parent mailhandler class not send "blank body" error if you have attachments
- make both differential and maniphest append a list of attachments to the body if any exist
- BONUS - made the cc stuff work in Maniphest
Test Plan: I haven't actually tested this yet. :( i need to figure out how to send a mail with an attachment from the command-line and figured I'd serve this up first.
Reviewers: epriestley
Reviewed By: epriestley
CC: aran, Korvin
Maniphest Tasks: T2012
Differential Revision: https://secure.phabricator.com/D3868