Refactor API structure, change to simple service

[SomeMoosery]

Since we are moving to running our API functionality to lambdas behind an API Gateway, we need to refactor the main part of our codebase.

We should no longer have a Go-based REST API, but instead a simple Golang program that runs a timer (we can flesh this out as we develop) and queries MongoDB to send out notifications to users (we can also flesh this out thinking in terms of bottlenecks => SQS, etc)

• remove subscribe/unsubscribe functionality from REST API
• refactor API a simple Go program
• deploy this program on 2 EC2 instances (for beta) in the 2 private subnets of our VPC, behind an ALB

[SomeMoosery]

I'm on this