Adapted the tests suite to work with salt-testing
Remove the now unnecessary `saltunittest`. Moved remaining functionality to `integration`.
Adapted code fix `sys.path` in case called from `__main__`. Adapted to salt-testing.
Make sure every test module is runnable by `__main__`.

* Double to single quotes
Install Salt Testing from git
Update `sys.path` before import salt. This way salt does not need to be installed.
Update copyright years of changed files. Added `__main__` execution to `tests/integration/states/pip.py`.
Added support for `__main__` execution and formatting fixes.
Added support for `__main__` execution and formatting fixes.
Added support for `__main__` execution and formatting fixes.
Added support for `__main__` execution and formatting fixes.
Added support for `__main__` execution.
Only update `sys.path` once.
Make use of the `SaltTestcaseParser` added to salt-testing.
Let's make use of salt-testing code coverage testing option parser.
Remove debug logic to test coverage.
Reuse salt-testing shell test case.
Removed duplicate variables moved some others.
Re-use salt-testing mixin.
Add `tests_require` to the setup arguments.