journal plugin: put the journal file in the right directory

Here right directory means the top log job result directory,
along with the job id file and the job.log file, etc.

Looks like there was a change in the meaning of `job.logdir`
and because of that, the journal plugin was saving the file
one directory up the tree.

Also, we needed the job logdir as part of the test state, just
like we need the job unique id.

Signed-off-by: Cleber Rosa <crosa@redhat.com>
docs/index: Reorder contribution guide order

It should go last in the list of topics, preceding only
the API docs.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
docs: Updating test references

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
docs: Update env variables documentation

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
Merge pull request #209 from lmr/docs-update

Docs update
Merge pull request #207 from clebergnu/journal_location

journal plugin: put the journal file in the right directory