Call start_file_logging inside avocado.job.

Call start_file_logging inside avocado.job, so Test Results
just need to use output_manager/stream object.

Signed-off-by: Ruda Moura <rmoura@redhat.com>
avocado.plugins.vm: Use self.stream.debuglog.

Signed-off-by: Ruda Moura <rmoura@redhat.com>
avocado.plugins.jsonresult: Use self.stream.debuglog.

Signed-off-by: Ruda Moura <rmoura@redhat.com>
Merge pull request #74 from ruda/job_owns_start_file_logging

Job  class owns execution of start_file_logging()
avocado.utils.virt: Improve implementation.

Improve the current implementation by adding properties
to get status, names and domains. Add support functions
to start, stop, resume, suspend, shutdown, etc machines.

Clear documentation about what kind of snapshot: system checkpoint.

Signed-off-by: Ruda Moura <rmoura@redhat.com>