JCLOUDS-150 - Removal of async from AWS - specifically EC2

...and EC2-related elsewhere. Also moved *Client -> *Api, and moved
everything from .../services to .../features, and threw in a bunch of
Optionals to fit the EC2Api approach.

And a very big tip of the hat to nacx for figuring out the generics
stuff my brain just could not handle. =)
JCLOUDS-151 - CloudStack refactored to remove async, *Client renamed to *Api.
JCLOUDS-149: Reuse checkstyle configuration