The name parameter is optional for the CopyImage API call of ec2.

Make the name parameter optional for the copy_image method. The default value is the same as that
of the source AMI being copied [1].

[1]: http://docs.aws.amazon.com/AWSEC2/latest/APIReference/ApiReference-query-CopyImage.html
Add unit test for the CopyImage API.

The test case covers two scenarios:
    1. Where all the parameters are passed to the API call.
    2. Where the name parameter is skipped. As per the
    documentation, the name of the source AMI will be used in such a
    case.
Adding API reference for boto.swf.layer2.
Merge pull request #1712 from oozie/swf_l2_ref

Adding API reference for boto.swf.layer2
Fixes #1679, #1566 - Altered DDBv2's ``batch_write`` to appropriately queue & retry unprocessed items.
Added ``dry_run`` to. All. The. Things.
Added support for modifying reserved instances in EC2.
Merge branch 'ec2-dry-run' into develop
Merge branch 'ddbv2-batch-write-fix' into develop
Merge branch 'ec2-modify-ri' into develop
Updated release notes for everything that's been merged.
Bumping version to 2.13.0
Merge branch 'release-2.13.0' into develop

* release-2.13.0:
  Bumping version to 2.13.0
Readded the dev release notes.
Fixed EC2 test failures due to the method signature changes from dry-run.
Adding unit tests for boto.swf.layer2.Domain
New unit test for boto.swf.layer2.Decider
New unit test for boto.swf.layer2.ActivityWorker
Addingw unit tests for boto.swf.layer2 types.
Added docs for apps that build on top of Boto.