feat: Add application port configuration

See merge request !5

Apply fixes from ucam-observe-remote-server

See merge request !3

Adds .flake8 file to the boilerplate.

Corrects error in gitlab CI configuration which causes tests to run
twice.

Moves tests module to be a part of the root package - in line with
project style throughout DevOps.

Resolve "Make healthcheck naming consistent with django boilerplate"

Closes #2

See merge request !2

Init commit

See merge request !1