Tests: First batch of changes on refactoring test cases
This is the first part of a larger effort to refactor some of our test cases structure.
Main changes introduced are:
- Using pytest as the testing framework to organize and mark test cases.
- Replacing custom bash scripts with test cases discovery.
- Integrating pytest-cov plugin to easier coverage collection and reporting.
- Marking remote test cases to being able to pick those during run.
- Abstracted remote test cases configuration in a base class.
- Consolidating pytest, coverage and tox configuration in a single tox.ini file.
- Removed some Python 2.5 support and replaced custom compat checks with six.
- Replace unittest.TextTestRunner.run by unittest.main (cherry-picked from f5dab5ca76, thanks @franferrax !)
gabrielg5