adding a formula for duff

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Formula/duff.rb

@@ -0,0 +1,17 @@
+require 'formula'
+
+class Duff <Formula
+  url 'http://prdownloads.sourceforge.net/duff/duff-0.4.tar.bz2'
+  homepage 'http://duff.sourceforge.net/'
+  md5 '9767e471232c1b4ee553ae40dbe60464'
+
+  def install
+    system "./configure", "--disable-debug", 
+                          "--disable-dependency-tracking",
+                          "--mandir=#{man}",
+                          "--prefix=#{prefix}"
+    # this needs to be executable, but isn't for some reason...
+    system "chmod 755 ./install-sh"
+    system "make install"
+  end
+end