Replace exit() by sys.exit()
Replace exit() by sys.exit()

sys.exit() is considered good to use here.

Change-Id: I396879c21707fa85fa5026eed99e627ac715b7b1

cernops/nova,rahulunair/nova,vmturbo/nova,bigswitch/nova,phenoxim/nova,BeyondTheClouds/nova,klmitch/nova,jianghuaw/nova,cernops/nova,BeyondTheClouds/nova,vmturbo/nova,cyx1231st/nova,NeCTAR-RC/nova,dims/nova,klmitch/nova,gooddata/openstack-nova,CEG-FYP-OpenStack/scheduler,Juniper/nova,mikalstill/nova,vmturbo/nova,phenoxim/nova,jianghuaw/nova,rahulunair/nova,alaski/nova,sebrandon1/nova,BeyondTheClouds/nova,klmitch/nova,zhimin711/nova,mahak/nova,gooddata/openstack-nova,mahak/nova,dims/nova,bigswitch/nova,hanlind/nova,NeCTAR-RC/nova,rajalokan/nova,sebrandon1/nova,cyx1231st/nova,rajalokan/nova,mikalstill/nova,sebrandon1/nova,rajalokan/nova,openstack/nova,jianghuaw/nova,mikalstill/nova,Juniper/nova,cloudbase/nova,jianghuaw/nova,klmitch/nova,alaski/nova,vmturbo/nova,rajalokan/nova,mahak/nova,cloudbase/nova,cloudbase/nova,rahulunair/nova,Juniper/nova,gooddata/openstack-nova,openstack/nova,hanlind/nova,CEG-FYP-OpenStack/scheduler,gooddata/openstack-nova,zhimin711/nova,cernops/nova,hanlind/nova,openstack/nova,Juniper/nova