virttest.utils_test: Fix submodule importing

Due to a very bad mistake of mine, I hose the ability
to access utils_test.qemu and utils_test.libvirt. By
importing libvirt and qemu internally those problems
should be fixed. Sorry guys.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
virttest.staging: Fix importing problem and interface change

Turns out staging also needed __init__.py fixing. Sorry
about that once again.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>