check-all: allow to control logging level from commandline

Change-Id: I8f506e0e491c1eb0df48ca668ad9f9035671b5dd
Reviewed-on: http://review.couchbase.org/38682
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Brett Lawson <brett19@gmail.com>