Report reasons: fade out on message report

This is a tag onto reddit/reddit@85a9223 and reddit/reddit@76858eb99.  Report
reasons weren't originally supported for PMs, so we returned early and didn't
call `form.fadeOut()`.  Now that we use the report reasons box everywhere, we
need to handle the form for everything, too.

[Reported][0] by /u/psdtwk.

[0]: https://www.reddit.com/r/bugs/comments/2p6m56/
Consistencize account text, part 2

While looking at reddit/reddit#1043, I was reminded that the work in
reddit/reddit@d2e2cef was incomplete, so I did a bit of `ack`ing and came up
with this set of changes.  This should be a pretty good set of changing login,
logged in, log out, logged out, etc. to the "sign out" equivalents, and
"register an account" and friends to "create an account".

There are a bunch of variable names and endpoints around that I didn't touch,
because that would break all sorts of things.  This *should* be only including
text directly shown to users (usually passed through `_()`) or indirectly shown
via the API docs.
Reports: fix in modmail

When a user reports a message, we've been checking to make sure it's actually
sent to them.  However, when a message is sent to a subreddit's moderation
team, any member of the mod team should be able to report the message, despite
it not being sent to *them*, directly.

We now extend the check to also check for moderator status if necessary.

[Reported][0] by /u/psdtwk.

[0]: https://www.reddit.com/r/bugs/comments/2p6m56/i/cmuw61w