Proof of concept API quality checking

Here's something i played around with for a couple of hours, I think there is some potential here but it's probably best to discuss it before going any further.

This proof of concept script looks for the following errors:

 * Base driver shouldn't have any ex_ methods
 * Base driver shouldn't have any methods with ex_arguments
 * Driver implementation shouldn't have methods that aren't defined in the base driver, unless prefixed by ex_
 * If a base driver method accepts an argument then a driver implementation should accept that argument
 * A driver implementation shouldn't accept any additional arguments that aren't prefixed with ex_

This has 70 matches - though a lot are false positives because ``create_node`` uses kwargs for things like image, size, etc. I don't really like that it does that...

But there are real matches - should ec2's list_snapshot be ex_list_snapshot for example.