Application emails - move over paste and files

Summary: Fixes T3404 (post D11565), fixes T5952. This infrastructure has been getting deployed against Maniphest and its time to get these other two applications going on it.

Test Plan: created an email address for paste and used ./bin/mail receive-test ; a paste was successfully created

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T5952, T3404

Differential Revision: https://secure.phabricator.com/D11570