Set unixsocket to undef in redis class

After [1], redis class does not longer accepts boolean as value for
unixsocket, so let's undefine it. Note that this has the effect of
enabling unix socket in redis but I don't see a way to get it disabled
after the patch.

To minimize risk, i'm setting permissions of socket to 0700.

[1] 502ff38c8c

Change-Id: Ic967d9446ef68a0257b9448bc8f3f3b664d776e0

packstack/puppet/modules/packstack/manifests/redis.pp

@@ -10,6 +10,7 @@ class packstack::redis ()
       port       => $redis_port,
       appendonly => true,
       daemonize  => false,
-      unixsocket => false,
+      unixsocket => undef,
+      unixsocketperm => '0700',
     }
 }