[3] Allow b5-init of a private repositories skeleton using ssh instead of https

Closes #3

See merge request build/b5!8

Refactor argument parsing and use it as a starting point for testing

See merge request build/b5!9

refactor(3): Move the functionality of the __init__ to a get_url() method which saves the result to a class property on the first call

build(gitlab#3): Add b5-init check whether skel is in a private repo or not, use ssh in case its a private repo

Introduce pylint

See merge request build/b5!6