license the webapp under the AGPL 3+

This means that anyone serving up the webapp to users as a service
(ie, without providing any git-annex binary at all to the user) still needs
to provide a link to the source code for it, including any modifications
they may make.

This may make git-annex be covered by the AGPL as a whole when it is built
with the webapp. If in doubt, you should ask a lawyer.

When git-annex is built with the webapp disabled, no AGPLed code is used.
Even building in the assistant does not pull in AGPLed code.

Assistant/WebApp/DashBoard.hs

@@ -2,7 +2,7 @@
  -
  - Copyright 2012 Joey Hess <joey@kitenet.net>
  -
- - Licensed under the GNU GPL version 3 or higher.
+ - Licensed under the GNU AGPL version 3 or higher.
  -}
 
 {-# LANGUAGE CPP, TypeFamilies, QuasiQuotes, MultiParamTypeClasses, TemplateHaskell, OverloadedStrings, RankNTypes #-}