Updating lab3. Details about the update are availabe on Piazza, if necessary.
Merge branch 'lab2' into lab3

Conflicts:
	fuse.cc
	yfs_client.cc
	yfs_client.h
Implement mkdir()
Implement fuse() and bug fixes, lab 3 test a passed
Fix buffer construction bug when there exists null char
Wrap lock instructions around requests, finish Lab 3