Implemented SourceObjectPresentTest.SetUp.
Implemented SourceObjectPresentTest.SetUp.

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