Hey all, I am digging through the sqlline logging options, it appears to
just use DRILL_LOG_DIR /sqlline.log and sqlline_quries.json.

Ideally, I'd like the ability to specify SQLLINE_LOG_DIR,
SQLLINE_LOG_PREFIX, and SQLLINE_QUERY_LOG_PREFIX in the drill-env.sh, this
would allow for more flexibility in bringing together users logs, if I
could have a centralized conf directory (which I do for my Mesos setup,
using MapR-FS, and a centralized log repo, it makes things much easier to
troubleshoot. If users install their own drill, then they can put the logs
where ever they'd like :)

Basically the changes we'd need is to check for those variables in
drill-config.sh, and set them to the current defaults (if not set), then an
update of the sqlline script right?  I am happy to contribute here, but I
am not sure which files would need to be changed (the .bat, ones?)  nor am
I confident that I am not over simplifying this... I'd welcome thoughts
before filing a JIRA or trying a pull request.