add read & write into the exception.cc
basic test environment for the u2kmemcpy
Merge branch 'master' of github.com:popacai/TQOS

Conflicts:
	code/userprog/syscommon.cc
implement all syscommon function
CAUTION!!!!!!!
    Reading may result in failure!
    Check after or before!!!!!!

    This should be handled in system call checker.

    This is extremely important!