As per #470, tasks should now be able to provide per-result artifacts. Change the bodhi_comment_directive, and provide the link to the specificresult in resultsdb.

This will require

• add resultsdb-frontend base-url to the libtaskotron's config
• resultsdb_directive to have a side-effect of adding a special key (most likely a special section, in which the key then will be added) for the result's ID, or the whole URL.
• bodhi_comment_directive should look for the result-id/URL, and fall back to the old style (link to the complete log) if not found