my solution to lab2
Merge branch 'lab2' into lab3
extentserver setAttr done!
finish setattr() in fuse.cc and yfs_client class
Merge branch 'lab3' of https://github.com/OscarLiXi/DS2014 into lab3

Conflicts:
	yfs_client.cc
fix grammar error
fuse read done!
finish read() in fuse.cc and yfs_client
Merge branch 'lab3' of https://github.com/OscarLiXi/DS2014 into lab3
fix bugs and add print for read operation
fix bugs
Merge branch 'lab3' of https://github.com/OscarLiXi/DS2014 into lab3
fix bugs of read string
fix bug in yfs_client, when offset is great than the size of file, append
Merge branch 'lab3' of https://github.com/OscarLiXi/DS2014 into lab3
fix the bug of write, if offset is larger than file size, then append. if not, replace. Plus,size of buf array is always 4096, should get the real buf using write_size
Bugs
Bugs Fix
Merge branch 'lab3' of https://github.com/OscarLiXi/DS2014 into lab3
lab3 done!