Fix organization logos with restrictive Content-Security-Policy

[neilmb]

How to reproduce

1. Visit https://datagov-harvest-dev.app.cloud.gov/organization_list/

Expected behavior

Organization logos are (mostly) shown

Actual behavior

Most of the logos are missing

Sketch

To be able to show images for all the different organizations while we have a restrictive Content-Security-Policy, we need to know what domain the images will be coming from. We have https://github.com/GSA/logo where we have done this in the past, so we need to redouble our efforts, downloading the images from the URLs that organizations have provided, uploading them into that github repository, and then changing the logo URL in the harvester database to the new one that starts with https://raw.githubusercontent.com/

[neilmb]

This also applies to https://catalog-beta.data.gov/organization and changing it in the harvester database should fix it there too. We do need to make sure that https://raw.githubusercontent.com is in the img-src of the datagov-catalog CSP.