avocado: Create sysinfo in more points of the job execution

Take system info in more opportunities:

1) Start job
2) End job
3) Start test
4) End test

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
docs: Add Results Specification

That explains the dir structure for avocado test results.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
avocado.sysinfo: Fix bug registering post test loggables

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
selftest/unittest: Add another sysinfo unittest

This time, using the Sysinfo Logger class.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
Merge pull request #104 from lmr/results_spec

Results spec