Added sysctl -p in step 1 to activate changes in /etc/sysctl.conf in ubuntu
Added sysctl -p in step 1 to activate changes in /etc/sysctl.conf in ubuntu

Change-Id: I8cd980e9b7be7b7e5a462976ff37b960fcbf8fd0
backport: havana
Closes-bug: #1250678

kairoaraujo/openstack-manuals,openstack/openstack-manuals,Akasurde/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,saeki-masaki/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,Akasurde/openstack-manuals,saeki-masaki/openstack-manuals,openstack/openstack-manuals,kairoaraujo/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,gongysh2004/openstack-manual,openstack/openstack-manuals,gongysh2004/openstack-manual,openstack/openstack-manuals,potsmaster/openstack-manuals,potsmaster/openstack-manuals