this patch implements few missing options in xl so that it can be

this patch implements few missing options in xl so that it can be
used as a replacement of xm in xendomains:

- dryrun and quiet, long options to xl create;

- l, option to xl list.

printf_info is now used to print the configuration of the running VMs so
the output has been reformatted to be similar to the output of xm list -l.

There is still one command used in xendomains that is not implemented in
xl and not covered by this patch: xm shutdown. However a patch has been
sent to the list in the past and we are expecting a new version of it
soon.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>