TravisCI: get the tests running again
try to fix the DistributionNotFound error
add pathlib as a dependency for every old python version in tox
change the default python to 3.4 (even if pathlib is among the dependencies, it can lead to a failure)
fix the ~/.virtualenvs already existing error, and workaround it for TravisCI
fix test_restore globbing and output checking to work with different Python versions