National/community portal proof-of-concept

[fbacall]

Summary of changes

• Adds configurable "communities" with custom front pages ("portals") that have a predefined set of filters applied.
• Optionally direct users to local national community portal using IP geolocation*.
• Adds ability to disable registrations by IP geolocation*.

* Requires MaxMind geolocation database: https://dev.maxmind.com/geoip/geolite2-free-geolocation-data?lang=en

Motivation and context

ELIXIR-UK DaSH grant

Screenshots

Banner on front page:

Portal:

Checklist

• I have read and followed the CONTRIBUTING guide.
• I confirm that I have the authority necessary to make this contribution on behalf of its copyright owner and agree
  to license it to the TeSS codebase under the
  BSD license.