* Work in progress...
* Finish first pass draft of MessagesDynamoDb
* Use begins_with everywhere for destination device id
* Remove now unused methods
* First basic test built
* Add another test case
* Remove comment
* Verify more of the message contents
* Ensure all methods are tested
* Integrate MessagesDynamoDb into the MessagesManager
This change plugs the MessagesDynamoDb class into the live serving
flow in MessagesManager.
Tests are not yet as comprehensive for this big a change as they
should be, but they now compile and pass so checkpointing here with a
commit.
* Put DynamoDB before RDBS when deleting specific messages
* Extract method
* Make aws sdk version into a property
* Rename clientBuilder
* Discard messages with no GUID
* Unify batching logic into one function
* Comment on the source of the value in this constant
* Inline method
* Variable name swizzle
* Add timers to all public methods
* Add missing return statements
* Reject messages that are too large with response code 413
* Add configuration to control dynamo DB timeouts
* Set server timestamp from the ReceiptSender
* Change to shorter key names to optimize IOPS
* Fix tests broken by changing column names
* Fix broken copyright template output
* Remove copyright template error text
* Add experiments to control use of dynamo and rds in message storage
* Specify instance profile credentials for the dynamic configuration manager
* Use property for aws sdk version
* Switch dynamo to instance profile credentials
* Add metrics to the batch write loop
* Use placeholders in logging
