(gh-477) enables root for non-root users on ec2 hypervisor

- root login is not possible on ubuntu-amis
- provision is not possible without root

This Patch enables root when the host['user'] differs from "root"
(gh-477) enables root for non-root users on ec2 hypervisor

- fixes codestyle
- fixes tests
(QENG-1449) proxy package managers before configuration/validation...

... of hypervisor SUTs

- run proxy_package_manager for each hypervisor before
  configure/validate step