This uses the to-markdown.js library to do all the hard work of
parsing HTML and turning it into markdown and not e.g. uploaded files.
Tweaked by tabbott to better scope when it activates to just include
pastes of HTML content.
Fixes#5853.
This change prepares us to have the server send avatar_url
of None when somebody wants a gravatar avatar (as opposed
to a user-uploaded one).
Subsequent commits will change behavior on both the server
and client to have this happen. So this commit has no-op
code for now, but it will soon use the fallback-to-gravatar
logic.
Andy Perez
Garvit
rht
Tim Abbott
Steve Howell
Umair Khan
Pweaver (Paul Weaver)