Create an authenticated client for DynamoDB.

Create a lock table in DynamoDB and wait until it is in "active" state.

Create the lock table in DynamoDB if it doesn't already exist.

Delete the given table in DynamoDB.

A bare-bones counting semaphore implementation based on: http://www.golangpatterns.info/concurrency/semaphores.

ddbsync requires the DynamoDB table to have a primary key with this name.

For simplicity, do all testing in the us-east-1 region.

Default is to retry for up to 5 minutes.