Change the output of qemucapsprobe to record the commands used for
querying. This allows to easily identify which reply belongs to which
command and also will allow to test whether we use stable queries.

This change includes changing dropping of the QMP greeting from the file
and reformatting of the query and output to stdout.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>