GitLab Geo: Display Attachments from Primary node

Merged Gabriel Mazetto requested to merge patch/geo-display-attachments into master

GitLab Geo (#76 (closed)) does not store attachments user uploaded files on secondary nodes yet. This is a workaround to get images/attachments link in a working state, even when the files are not in that node.

Banzai will build URLs using Geo primary URL for relative URIs expansion.

Fixes #414 (closed)

Checklist

  • Build images URLs based on primary node URL
  • Specs