Support authentication for tools that do not support it. mongo{top,stat} advertise support but do not call auth() anywhere.

Mongodb tools mongotop and mongostat do not support authentication. But they advertise support it in the --help message.

Triple verified my admin username/password is correct but was unable to connect.
An strace confirmed there where no authentication attempt.

After a look at tools/

.cpp I realized authentication advertisement is inherited from base class but auth() is not called anywhere in doRun().

Since I am not a C++ guy I cannot create a good enough pull request so I opened this issue.

Feel free to correct me if any of my assumptions are incorrect!