* Fix Dockerfile build
The Docker build used a 2-step installation of requirements
and application.
This was broken by #272.
Fixes#300
* Add dependencies cache for docker build
Caching installation requirements saves time when building
* Add PyInstaller build
Use PyInstaller to generate single binary.
Use staticx to generate a single static binary.
Resolves#301
* Add test Makefile target
Add test to Makefile.
Add requests_mock to dev dependencies.