SELinux: Allow boot time and init disabling

  SECURITY_SELINUX_BOOTPARAM
    Enables the boot time disabling of SELinux via
    selinux=0 in the kernel command line during boot time
    (set to 0 by default, clearly)

  SECURITY_SELINUX_DISABLE
    Enables init triggered disabling on SELinux during
    runtime

Signed-off-by: KhasMek <Boushh@gmail.com>