Make it easier to die properly

Imply str() on msg so that anything can be passed

include/sardine.py

         self.pluginpath = path
 
     def die(self, msg, rv=9):
-        sys.stderr.write(msg + "\n")
+        sys.stderr.write("%s\n" % msg)
         self.exit(rv)
 
     def exit(self, rv=0):