Initial implementation for clustered slave

SlaveMode now fires up one or more slave_worker instances, which do the
underlying listening and streaming.  We trade memory (each slave_worker needs
to have its own rewind buffers) for spreading CPU load out across multiple
cores.

Current implementation works and can hand off successfully, but needs a little
more load testing.
Refine handle passing during slave handoffs

During a slave mode handoff, we have the tricky task of passing a handle from
a cluster worker to the cluster master, on to the new cluster master, and then
on to the new cluster workers.

As of Node 0.10, normal server handles don't seem to do well with that.

We're now passing the underlying handle from old -> new without the server
wrappings (so that the child_process code doesn't trn on listening in the new
cluster master), and then passing the fd number on to the cluster workers.
Add a new 'silly' logging level for super-verbose output
Logger: Clean up w3c file opening logic
Add overloaded console logger with ability to ignore certain log levels
Fix handoff error if last listener was lost before sending

When a handoff starts, each slave puts together an array of listeners that
are "boarding"—waiting to be sent to the new process.  When it gets an ack
that the listener arrived, it runs a function to send the next listener out
of that list.  When there are no more listeners waiting to board, the ack
function triggers the callback.

If a listener has disconnected in the time between assembling the list and its
turn for flight, the sending code skips the listener and moves on to the next
one.

The bug was that if the last listener in the boarding line had dropped, the
ack function never got a chance to trigger the callback.  This fix adds an
additional spot to trigger the callback in that situation.
Bump version to 0.3.0; Switch back to node-icecast master; Add Roadmap

* node-icecast: Switch back to non-forked node-icecast, changing up how we do
  our different initial metaint using method suggested by TooTallNate
  -- https://github.com/TooTallNate/node-icecast/pull/10
* Bump to 0.3.0
* Add ROADMAP laying out big themes for versions between here and 1.0
Merge pull request #3 from StreamMachine/ClusteredSlave

Add Cluster Support for Slaves