Use a specific script to set the capabilities

Use a specific script to set the capabilities

Instead of having the capabilities to be set automatically,
it will be up to the user to set them through a specific
script 'lxc-setcap'.

After installing the lxc tools, if we want them to be available,
for a non-root user, lxc-setcap will set the needed capabilities.
If, after thinking it, we want to remove the capabilities,
the 'lxc-setcap -d' will do this for us.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Acked-by: Guido Trotter <ultrotter@google.com>