Spurred on by #1989 and #1995 (potentially also spurned), we discussed how best to overwrite static content for custom deployments. Mainly impacts the background/favicon

We should rely on collectstatic and add in an appropriate STATICFILES_DIRS.

Currently it's set here in the base settings:

Seems like we could change this to something like:

STATICFILES_DIRS = [
    os.path.join(BASE_DIR, 'static'),
    os.path.join(BASE_DIR, 'static-overrides'),
]

Then we'd just have a .gitignore in static-overrides and let repos store non version controlled content there