avocado.plugins.vm: Use relative test paths instead of absolute ones

When running tests on a VM, the tests are copied to it
and subsequently executed using absolute paths. While
this is technically correct, it is better to replicate
the dir structure of the tests in the source machine.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
avocado.plugins.vm: Display Job ID properly in the CLI

Set a Job ID in the host, and force the avocado command
run using it inside the VM. With this, we get to display
that information to the user.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
avocado.plugins.vm: Display job log before test list

Right now, as we parse and display results all at once,
displaying the job log doesn't matter much. Therefore,
let's keep the output symmetrical to the one obtained
running avocado in the host.

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