Move static coverage and docs sites to S3

Ghost User
2020-01-30T13:33:19+01:00

### Description
Move static coverage and docs sites to S3.

I have created the following AWS service instances:
- Two S3 buckets, called `thalia-coverage` and `thalia-documentation`.
- A policy that allows the `gitlab-deploy` user (who is also used to deploy the review environment) to manage files in those buckets.