AWS backend

[bobby]

Extracting and abstracting the main components in the API:

• Event Log (producer and consumer)
• Database/Index (writer and reader)

Then, implementing AWS versions of these components:

• Event Log => AWS Kinesis
• Database/Index => AWS DynamoDB/RDS/etc.

Tasks:

• [x] Extract event-log as top-level abstraction
• [x] Replace database.clj with read protocol for indexer in api
• [x] Implement Kinesis event-log
• [x] Implement DynamoDB indexer, with no-op writer (if that can be handled automatically between Kinesis and DynamoDB)
• [ ] Implement a top-level entrypoint for building AWS stack (perhaps polymorphic on a :stack key in config or something)