avocado.plugins.virt: Port to output.View()

Although not completely fixed, the refactor lays the
ground for future transparent notification.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
avocado-virt: Add initial selftests

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
Merge pull request #5 from lmr/sprint-14

Sprint 14