Fix genconfig - missed one import from oslo cleanup

The oslo cleanup Ib020cd4c3464f1c994a6d77f4b894f41b99e6d02 removed
importutils, we forgot to fix the generator.py

Change-Id: Ib353f7e0fee5f7ed06f4b45f98fb1a1bf6abfc9e
Merge "Fix genconfig - missed one import from oslo cleanup"
Add notification for server group operations

Currently, there is no notification when create/update/delete
server groups, this caused some 3rd party client cannot know
when those operations are finished.

The fix was adding notifications for those operations.

DocImpact
The wiki page https://wiki.openstack.org/wiki/SystemUsageData
needs to be updated once this patch was merged.

Change-Id: Ia1f4a6752668ddb73ebb8faf525b58a28d183754
Closes-Bug: #1343200
Merge commit 'refs/changes/41/127941/3' of git://gold.eng.hq.xensource.com/git/github/openstack/nova into tmpbranch