common: move httplib2 back into common, add libselinux

both httplib2 and libselinux can be requirements for ansible.
ntp: the ntp_server may be set in group_vars, but did not work

Seems like common/vars could be a more intuitive place for public
common vars
Packstack: first commit of packstack nova/neutron aio
Packstack Neutron: updates to neutron install, some fixes etc..
common: move yum -y update to common and reboot
update to packstack