LocalStack

[kylerwsm]

Problem

So, we need a S3-like service for local development. We want it to be accessed without credentials. And we want something that is contained only within our local development environment. Enter LocalStack, an easy-to-use test/mock framework for developing cloud applications.

Closes #117.

Solution

• Introduce dockerised version of LocalStack in our docker compose
• Created an init script (heavily inspired from formsg's version)
• In development, LocalStack is injected in-lieu of S3ServerSide.
• Updated .gitignore to ignore local files created by LocalStack

Notable changes

• Since LocalStack runs locally on http, https is disabled in development.
• Since file links on localhost is not a proper url, url validation on Sequelize is disabled in development.

Notes

• This PR should be merged after file-upload-frontend
• This is a working prototype, and subsequently, I will be refining it further.