Remove job logs database keys

Now that the job logs are nicely arranged in a directory, this sort key
functionality is no longer necessary.
Fix pgrep usage logic
Merge pull request #1422 from matthewrmshin/pgrep

Fix pgrep usage
Merge pull request #1391 from matthewrmshin/remove-job-logs-db-keys

Remove job logs database keys
rose host-select: improve performance

Don't SSH all hosts if ranking method is random and there is no
thresholds to consider. Shuffle host list, and return 1st available
host.