Start migrating to Version=2014-05-26.

Zones are re-introduced. There are only certian resource types you can
create in each zone, tracked in Zone.available_resource_creation.
Similarly, only certain Disk types are supported in each Zone, tracked
in Zone.available_disk_types

Two simple helper methods for asking if a given resource type or disk
type can be created in a given region.

Instances now have a Description, ClusterId and OperationalLocks.
Add Zone unittests
Fill in the Zone model and EcsConnection methods
Have Instance handling know about Zones
Update the Disks APIs.

Disks are now a top-level object. DescribeDisks is created, and
DescribeInstanceDisks is a subset of its functionality.

The Disk object model is now very much more full.
Replace functionality of obsolete Disk APIs
Implement ResetDisk and DescribeClusters
Add functional tests. Move tests/ directory around
Small update to ali.py to make it more usable.

Now call it with -S ecs or --service=ecs. No more of this magical first
non-flag remainder business.
Adding some LICENSE headers to files
Fill in the Instance model some more, and assoc'd.

The CreateInstance and DescribeInstances Actions are substantially
changed, particularly relating to Disks. There's now a DeviceMapping
that I'm ignoring for now.
Fill in more chnages for 2014-05-26 for Snapshots.

* Add AutoSnapshot-related models and methods.
* Update DeleteSnapshot not to require DiskId.
* Update DescribeSnapshots to have all parameters optional and be paginated.
* Update DescribeSnapshots to be able to filter based on DiskId,
* InstanceId, and up to 10 (API-enforced, not in here) SnapshotIds.
* Update the Snapshot model to include SourceDisk information.
Doc updates.
Small cleanup. Fix problem in describe_disks

When passing disk_ids=['d1','d2'] as documented, we broke.
Update docstrings related to data disk at creation

The API is now very much more robust around additional data disk
creation. These should probably be wrapped up into a BlockDeviceMapping
object like in boto.
Whitespace and style changes.
Add a DeviceMapping class to handle DataDisk.n.*

The ECS CreateInstance API is pretty weird. Let's bundle up its
arguments into a suitably weird class and give that the "smarts" to
determine how to present itself for the API.
Version bump to 0.7 to incorporate 2014-05-26.