Set a posts replyToId before setting content

The setContent method, in order to determine storage format, utilizes
AbstractRevision::isFormatted.  This in turn checks the replyToId to
decide if a post is a topic title or not.  Topic titles are saved as
plaintext, regular posts are stored in the content format.  Because
we were setting the replyToId after setting the content, all content
was being stored as wikitext rather than html.

Change-Id: I24c84959347fd1fbb51841f1276eedcfaff8f2f4
Merge "Set a posts replyToId before setting content"