Expose the AWS SDK instance that aws-swf is using to set custom
AWS attributes
Add documentation to README
Allow newer versions of aws-sdk dependency to be used
Improve error handling in Workflow#startCb
Merge pull request #26 from mdlavin/allow-new-aws-sdk

Use a newer version of aws-sdk (and allow automatic updates in the future)
Merge pull request #27 from mdlavin/fix-startCb-error-handling

Improve error handling in Workflow#startCb
Merge pull request #22 from kenhkan/add-aws-ref

Expose the AWS SDK instance that aws-swf is using to set custom AWS attributes