Added tests for FileInode.
Added tests for FileInode.

Fixes #44.

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