Add complete list of requirements to requirements.txt
Add complete list of requirements to requirements.txt

From https://packaging.python.org/requirements/:
"
install_requires is a setuptools setup.py keyword that should be used to
specify what a project minimally needs to run correctly.

(...)

Whereas install_requires defines the dependencies for a single project,
Requirements Files are often used to define the requirements for a complete
python environment.
"

My previous treatment of requirement.txt file was not a standard one: it listed
only minimal list of requirements (including requirements of spam-lists: at
the time, I had not published it on PyPI yet and I used it as a git submodule).

This was both unnecessary, especially after I added the setup.py script with
install_requires, and unweildy: I couldn't update the requirements.txt file
by calling 'pip freeze' command.

piotr-rusin/url-shortener,piotr-rusin/url-shortener