We remember driver name in a new field 'drivername' within
private parallels connection structure. When a new domain
is defined we use this name to set corresponding virtType.
We set VIR_DOMAIN_VIRT_VZ for 'vz' driver and
VIR_DOMAIN_VIRT_PARALLELS for 'Parallels'.
Signed-off-by: NMaxim Nestratov <mnestratov@parallels.com>