[NRRPLT-7722] Python3 compatibility

[NRRPLT-7719] I executed the future module on VirtualCoach. Some builtin python functions are redefined, so pylint will issue warnings.

[NRRPLT-7719] Fixed bugs occuring in run_tests.sh: Checking for string types must use string types from the six module.

The W0622 (redefining builtin function) warnings of pylint are now disabled.

Additionally, the integration test now uses absolute paths for loading data.

[NRRPLT-7722] Made the code compatible with Python3.

[NRRPLT-7722] Adding some minor bugfixes.

[NRRPLT-7722] Adding more minor bugfixes.

[NRRPLT-7722] Update setup.py

Change-Id: Ibb59a6d2b71ed77170c636f2357c011f3e875ea0

 [NRRPLT-7722] Fix Makefile

Change-Id: Id723122f896e3d20a79bd1603a75452beeaa56f2

[NRRPLT-7722] Upgrade pip version

[NRRPLT-7722] fix pip version specifier in Makefile

[NRRPLT-7722] fix pylint

[NRRPLT-7722] Quote pip version in user_makefile. Force python2-compatible ipywidgets version

[NRRPLT-7722] fix version

Change-Id: I74c6ea95a537cfe03786c8cc15484581ca573e1c

[NRRPLT-7722] fix type check in oidc_http_client

Change-Id: I74d6d9c5059b659b50b9b6f2328a2c8832c3e330

[NRRPLT-7722] force check for pip version in pipeline

Change-Id: Ie09870af0dcf4f9af66f27d784a28f4eee285f22

[NRRPLT-7722] More robust ipywidget version requirement. Move test dependencies in separate file

Change-Id: I20c186cd07a7c34175b2b25cd4ff3a9222b7d782