Remove unused imports from neutron api

This patch removes conductor and security_group module which
are unused any more from neutron api.

Change-Id: I812f3038c5671e7605ebc01bb9cec77304269143
Merge "Remove unused imports from neutron api"
Merge commit 'refs/changes/41/127941/3' of git://gold.eng.hq.xensource.com/git/github/openstack/nova into tmpbranch