Get Unread Messages + info when submitting/commenting too often.

Get Unread Messages - Had to set curl option FOLLOWLOCATION for this to
work. Also for messages it doesn't use the /api/* url. See
http://www.reddit.com/dev/api#GET_message_{where}. I've only coded it
for unread messages. It is trivial to edit it for inbox/sent messages.

See http://www.reddit.com/dev/api#GET_message_{where} for details.

Also added a response for 'You are doing that too much, please try
again in xx minutes' messages (line 70)