add mock libvirtaio module + pylint fixes

qubes/vm/qubesvm.py

@@ -32,8 +32,6 @@ import os.path
 import shutil
 import string
 import subprocess
-import sys
-import time
 import uuid
 import warnings
 

test-packages/libvirtaio.py

@@ -0,0 +1,9 @@
+"""mock libvirtaio module
+
+WARNING: you did not import real libvirtaio module
+
+This is needed, because we don't currently ship libvirt-python for templates.
+"""
+
+def virEventRegisterAsyncIOImpl(loop):
+    pass