R1:97d74db98b8c

Add PhamePost body content to emails

Summary: Sends out the body of the post along with the details.

Test Plan: Write a new post, see body in email.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T9360

Differential Revision: https://secure.phabricator.com/D14431