io.js Working Groups

Based on the informal process we've already undertaken I've written up a more formal documentation and process around the idea of "working groups" and attempted to charter the ones that are already up and running.

The high level goals are to ensure that we don't prematurely break work off in to subgroups and also to ensure that the projects have real autonomy.

Need feedback, especially from @chrisdickinson and @rvagg to make sure this accurately describes Streams and Build.