Added a test target that uses fake buckets.
Added a test target that uses fake buckets.

BanzaiMan/gcsfuse,kahing/gcsfuse,GoogleCloudPlatform/gcsfuse,GoogleCloudPlatform/gcsfuse,jacobsa/timeutil,BanzaiMan/gcsfuse,GoogleCloudPlatform/gcsfuse,jacobsa/ratelimit,mbrukman/gcsfuse