switch to sha1sum because of homebrew breaking md5

Author: wfarr

files/brews/postgresql.rb

@@ -3,7 +3,7 @@
 class Postgresql < Formula
   homepage 'http://www.postgresql.org/'
   url 'http://ftp.postgresql.org/pub/source/v9.1.4/postgresql-9.1.4.tar.bz2'
-  md5 'a8035688dba988b782725ac1aec60186'
+  sha1 'c75fd5696af02a275a104260eac8b3a4abe35682'
   version '9.1.4-boxen2'
 
   depends_on 'ossp-uuid'