Add minimal test suite

[nuest]

• implement some tests, using https://docs.python.org/3/library/unittest.html
• tests run on Travis: https://docs.travis-ci.com/user/languages/python/

[ghost]

see 977ce08 for client side basic tests

[ghost]

included with 07a10686e041a6cfb9ba9572961787bda24801ea