Allow ssh access with sshpass to remote libvirt

Currently fuel-devops is able to manage envs on remote libvirt via qemu+ssh, but only with private key auth (path to this key is hardcoded).

Please add possibility to connect to remote qemu+ssh with ssh password provided from sshpass util.

Seems it works using fuel-devops from python script like this https://github.com/openstack/fuel-ccp-installer/blob/master/utils/jenkins/env.py

export SSHPASS=password
sshpass -e python env.py create_env

But it is not working for execute shell command, like http://paste.openstack.org/show/596727/