[MERGE] stable-2.15 to stable 2.16

['Viktor Bachraty' via ganeti-devel]

commit 008fd45761cde7979ba56d823fe79d94b032b91c
Merge: ed5786c b3c0fb0
Author: Viktor Bachraty <vbachr...@google.com>
Date:   Fri Apr 22 14:38:20 2016 +0100

    Merge branch 'stable-2.15' into stable-2.16
    
    * stable-2.15
      Allow newer cabal deps for latest Debian/Ubuntu