Document all responses

[scruffyfox]

Hey,

There's a few responses missing from the documentation which would be good to see added so we don't have to do a trial and error to see what they are.

http://developers.app.net/docs/basics/responses/

The ones missing off the top of my head are

• Following a user who has blocked you
• Uploading a file exceeding your storage size
• Exceeding your follow count (free users)

Would be good to see the error-stub so we can handle it properly for localisations and what not