Cleaning up changes from JCLOUDS-106
JCLOUDS-138. Add CloudStackImageExtension support.
JCLOUDS-101 - Add SecurityGroupExtension for compute

- Adds the SecurityGroupExtension to compute, with tests and stub
support.
- Gets everything else to actually build against this.
- Unifies on compute's IpPermission/IpProtocol, eliminating EC2's.
- Converters from EC2/Nova/CloudStack SecurityGroup (and rules, for
the latter two) to the compute SecurityGroup (and rules, etc).
- EC2SecurityGroupExtension and tests.
- AWSEC2SecurityGroupExtension and tests - depends on JCLOUDS-99.
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
JCLOUDS-126 - Support and tests for region selection in swift-keystone BlobStore