file logging for new make target

verbosity of logging is set to critical level by default

Change-Id: Ib67235254b518b7fa858e976ed071eca5a82e78c
Reviewed-on: http://review.couchbase.org/41058
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>