Add test which test nothing
Adds config for testr and updates cover section in tox.ini
Make tests as a Python package

(.venv)ash@ami:~% testr init
(.venv)ash@ami:~% testr run
running=python -m subunit.run discover .
Ran 1 tests in 0.000s
PASSED (id=0)
Adds coverage erase instruction to coverage report generation
Adds dependencies for tests coverage generation as external file
Adds forgotten reference to testrepository package
Run testr backends under `coverage run` command

The patch also adds the `.coveragerc` configuration with the `run` section
because there is no way to specify agrument parameters directly.
Fix version of python-subunit==0.0.18
Fix formatting of tox.ini
Coverage report include only pumphouse package
Rename tests-requirements.txt
Ignore temporary files for tests and coverage
Enhance sample test
Move test to the proper place
Add basic stuff for tests

The patch adds proper configs for executing tests and generating coverage
reports.