import and install gettext in vm_vdi_cleaner.py

importing some nova modules expects _() to be defined, so lets define it
before we start importing them.

Change-Id: I7f951a24c19a53434c090cd2c01eded77c703943

tools/xenserver/vm_vdi_cleaner.py

@@ -17,12 +17,14 @@
 """vm_vdi_cleaner.py - List or clean orphaned VDIs/instances on XenServer."""
 
 import doctest
+import gettext
 import os
 import sys
 
 from oslo.config import cfg
 import XenAPI
 
+gettext.install('nova', unicode=1)
 
 possible_topdir = os.getcwd()
 if os.path.exists(os.path.join(possible_topdir, "nova", "__init__.py")):