Changes to unix

Changes to unix:
commit 5ccab3c64a2e37903111755c6b99795c410bed0e
Author: Herbert Valerio Riedel <hvr@gnu.org>
Date:   Fri Nov 8 16:18:17 2013 +0100

    Add `cabal install` step to Travis CI script

    Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>