Introduce RunConfig struct

Introduce a RunConfig struct in preparation for making hypervisor
configurable.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
Make hypervisor configurable for run command

Add a '-p' command line option for making hypervisor configurable.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
Simplify Run function error handling

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>