data: Expect shell in /bin rather than /usr/bin

/bin is the canonical location for the bourne shell, not /usr/bin
(for systems that still stick with the historical split).

https://bugzilla.gnome.org/show_bug.cgi?id=786419

data/theme/parse-sass.sh

@@ -1,4 +1,4 @@
-#!/usr/bin/sh
+#!/bin/sh
 
 srcdir=`dirname $0`
 stamp=${1}