Note: we should probably rename it "setup()" to avoid confusion.

Also trying to fix NOX cmdline opt, but broken at the moment.

Controllers are no longer namespace-able, and all calls need one fewer
arg.

Also use more sensible temporary variable name.

We should check NOXController and RemoteController to make sure that
they are not broken, but I cannot do this at the moment.

Also switch from print to info statements, to enable a non-verbose
clean.  Instead of 'mnclean', now run 'mn -c'.

Now you can pass a topology name followed by params.  For example, to
create a switch with 3 hosts:

  sudo mn --topo single,3

Also print warning if user chooses a loglevel that will hide CLI output.