Removed unnecessary monkeypatching of __builtin__

Replaced it with explicitly importing the gettext function, which is
significantly more readable.

Change-Id: Ia0a7edcf685fb6e4052a8290367b233169529ab8

swift/proxy/server.py

@@ -27,6 +27,7 @@
 import mimetypes
 import os
 from ConfigParser import ConfigParser
+from gettext import gettext as _
 from random import shuffle
 from time import time