vds_installer: set proper exit code when success
vds_installer: set proper exit code when success

return 'True' actually causes process to exit with
non-zero code, hence failure.

Change-Id: If0f666ab45fb68cb50e1415d4a47df176496a12f
Signed-off-by: Alon Bar-Lev <2e3ceb4d37adc6ae3ccc00d3646e0e0a036ace03@redhat.com>

eayun/ovirt-engine,zerodengxinchao/ovirt-engine,OpenUniversity/ovirt-engine,zerodengxinchao/ovirt-engine,yingyun001/ovirt-engine,walteryang47/ovirt-engine,halober/ovirt-engine,OpenUniversity/ovirt-engine,halober/ovirt-engine,yingyun001/ovirt-engine,eayun/ovirt-engine,eayun/ovirt-engine,walteryang47/ovirt-engine,yapengsong/ovirt-engine,yapengsong/ovirt-engine,OpenUniversity/ovirt-engine,walteryang47/ovirt-engine,yingyun001/ovirt-engine,yapengsong/ovirt-engine,yingyun001/ovirt-engine,walteryang47/ovirt-engine,OpenUniversity/ovirt-engine,zerodengxinchao/ovirt-engine,halober/ovirt-engine,yingyun001/ovirt-engine,zerodengxinchao/ovirt-engine,OpenUniversity/ovirt-engine,eayun/ovirt-engine,eayun/ovirt-engine,yapengsong/ovirt-engine,halober/ovirt-engine,walteryang47/ovirt-engine,yapengsong/ovirt-engine,zerodengxinchao/ovirt-engine