Added AWSCredentialsProvider support via provider parameter to db-client.
Allow for binding to *client-opts* in test
Allow for local testing via AWS_DYNAMODB_ENDPOINT system property
-  AWS_DYNAMODB_ENDPOINT="http://localhost:8000" AWS_DYNAMODB_ACCESS_KEY="" AWS_DYNAMODB_SECRET_KEY="" lein test
- Formatting changes
- Updated README for provider paramater.
Merge pull request #28 from marcuswr/master

Add AWSCredentialsProvider support (marcuswr)