Application container plugins

Adding application container plugins: 
  * selinux (legacy)
    - No major change other than moving into its own plugin
  * libvirt-sandbox-lxc (new)
    - Uses libvirt-sandbox for container management
    - Uses IPTables for port-forwarding
    - WIP
Moved Node code into Runtime module
Updates shell exec and oo_spawn calls to go through container where applicable