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.

All commands should work now.

There is probably a better way of doing this, but currently
parseCustomFile can modify globals (e.g. TOPOS) as well as
instance variables (self.validate) and classes (e.g. MyTopo),
which are also in the global name space.

Inconveniently enough, lambdas don't seem to be full closures
in Python; if they were, this trickiness would be unnecessary.

Even so, using execfile() seems like it might be a bit dubious...

This increases flexibility by allowing a topology to be manually created
in Python, or specified using another format, without having to create
a Topo object first.

However, Topos are useful, and are still the default topology object!

Defining custom topologies, switch types, controllers, and hosts is now
much easier.  Plus, all Ripcord-specific stuff has been moved out.

'unpep8' script, which does most of the work.

- topo.py is still in pep8
- not all examples work, but this is due to other issues

Updated other files accordingly.

It's possible that mn_clean is a bit easier to read; mnclean may be easier
to type, however.

Added variables to Makefile so that source files are listed in a single
location.

This required a change to logging, which now uses a singleton pattern.

For all future checkins, 'make codecheck' should pass.

Switches and controller in root namespace only, for now.

Possibly useful for adding custom port mappings.

Now you can run a controller on a remote PC that is
not on the same pc as Mininet.

Also use indexing for DPIDs to avoid zeroed MAC

Auto MAC setup sets each host MAC equal to its DPID, which simplifies
debugging.

Auto ARP setup removes the need for broadcast support for ARP, which
enables a smaller NOX controller.

If ripcord.dctopo imports properly, then include its topologies in the
list of available ones.  Also replace topo.py with new generic
topologies and update paths.