Merge pull request #16 from HandsomeCharming/master

Added gfs_chksvc_t and implemented on_clnt_newchk
change the datastruct like gfs_chk_t and file_t for easier chunk management.
and now it is OK for continous write.
continous read(not tet)
continous read/write done!
add O_APPEND support
clean the no use code
rename libgfsclnt.a -> libgfs.a
add write test
add read_test
add head file of hash_table
add write_console_test and change init to gfs_init
merge