Revamp the directory structure and shape of imports?

[jfhbrook]

The directory structure of this module is basically exactly what nodejitsu was using in 2011/2012. Things have changed!

It would be cool, for instance, if instead of require('ecstatic').mime you could do require('ecstatic/mime').

It's not strictly necessary to move all of the modules around - can also add shim modules - but we might as well git mv some files while in here. Guessing based on how node handles importing nested thingers that we'd just make the directory structure flat.