Missing import in diskutils.py in host-installer

See this bug reported by a user: https://github.com/xcp-ng/host-installer/issues/13

The code is attempting to use the errno python library without importing it first.

Proposed patch: 

diff --git a/diskutil.py b/diskutil.py
index 8d0aa70..069d471 100644
--- a/diskutil.py
+++ b/diskutil.py
@@ -24,6 +24,7 @@
 from disktools import *
 import time
 from snackutil import ButtonChoiceWindowEx
+import errno
 
 use_mpath = False 

I take this bug report as an opportunity to state again that it would be easier to contribute to the installer if it was developed in a public git repository .