Cleans up neutron code

> was OK here, so why the change?

Originally my review comment, @jdaggett ;-) I made it because this seems like a comment for a jclouds-dev, not something a **user** of jclouds would expect in the Javadoc.

A user-facing description would be something like "Converts a string representation to the appropriate enum, with A, B and C special features" or so. But I don't really think we need that?