Provide Distribuuted operation locks for AwsVm and other resources #10
Description
We've run into at least one case where we managed to create duplicate issues because two carthage instances were using the same layout at the same time.
It would be cool if we had distributed locks for things like the AwsVm operation lock to prevent this.
We'd want any locks to time out if not periodically refreshed.
Take a look at https://aws.amazon.com/blogs/database/building-distributed-locks-with-the-dynamodb-lock-client/ for ideas on how to accomplish this with AWS resources.