Add a proper flow to set up the gdrive integration

[Zebreu]

Currently, the Google Drive integration requires a few extra steps not covered in the current repo:

1. Having a Google dev account
2. Enabling both Google Sheets and Google Drive API
3. Creating an Oauth client ID
4. Downloading a json credentials file and having it added to the docker image
5. Creating two pickle files (one for sheets, one for drive) through a manual authorization step through the browser when prompted by the application inside a docker container
6. Keeping the pickle files and adding them to the image to the root of the application/working directory

This isn't ideal and our steps aren't generically documented yet.

[Zebreu]

also dockerfile needs to be modified, e.g.:
COPY src/creds/gdrive_creds.json gdrive_creds.json
COPY drive_v3.pickle .
COPY sheets_v4.pickle .