pyLODE v3 server

[sharon-tickell]

I have found the embedded pyLODE server useful for local live LODE testing of my ontology servers, but is isn't currently included in the latest pyLODE versions.

This PR offers that functionality back again, in case it is also useful to others.

It includes:

• An updated pylode/server.py implementation that:
  • is compatible with the latest version of falcon
  • supports the same configuration options as the current pyLODE CLI
  • includes support for customisation of the server's favicon and stylesheet via environment variables similar to the pre-existing v2 support for GTAGID.
• Docker build tooling for the pyLODE server as either a standalone single-process HTTP server or as a WSGI application under GUnicorn
• Updates to the documentation to include information about the server again, and to make the docker-usage docs match what the Dockerfile actually does.