tests/rv_clearx.py: Removing clearx

It's a lot better to clean interface from rv_connect

Signed-off-by: Tomas Jamrisko <tjamrisk@redhat.com>
tests-spice.cfg, spice.cfg: Adding proxy test; removing clearx
Signed-off-by: Tomas Jamrisko <tjamrisk@redhat.com>
tests/rv_connect.py: Adding proxy and basic windows client

This adds ability to connect through proxy, basic windows
client connection and ability to restart x at connection.

Signed-off-by: Tomas Jamrisko <tjamrisk@redhat.com>
virttest/utils_spice.py: Fixes related to windows client

This adds ability to verify windows connection, adds ability
to restart x-server and install windows client.

Signed-off-by: Tomas Jamrisko <tjamrisk@redhat.com>