commands: fix minor bug start host vm

when catching exception for disk not found str.find() should be
> 0
commands: in restore host vm file is a param not an args

fixed the documentatio: file is a paramameters
command: start host vm: do not use 'str' reserved keyword
commands: report detailed instruction if a stopped domain is still there

when libvirt stops a domain you cannot restart it, in the traditional way
you have to resore it.
commands: push /etc/libvirt/networking/vlan.conf when starting a VM

call sync host vlan when starting a VM which has autostart active