Tests don't run propery #74

Expected result

I clone, install needle and then run tox. All tests should pass.

Actual result

[...] FAIL: test_existing_baseline_not_overwritten (tests.test_plugin.NeedleCaptureOverwriteTest)
[...] FAIL: test_baseline_is_saved (tests.test_plugin.NeedleCaptureTest)
[...]  FAIL: test_screenshot_is_cleanedup (tests.test_plugin.NeedleCleanupOnSuccessTest)

and many more. I have appended the full output as a file.

Reproduce

git clone https://github.com/python-needle/needle.git
cd needle/
mkvirtualenv needle 
pip install .
pip install tox
tox

Remarks

I did not find any further documentation on how to prepare the testing environment so this may be due to some missing configuration steps. If that is the case I'd like to point this issue into a "missing documentation" issue.

Environment

pip freeze needle==0.5.0 nose==1.3.7 Pillow==5.0.0 pluggy==0.6.0 py==1.5.2 selenium==3.8.1 six==1.11.0 tox==2.9.1 virtualenv==15.1.0

Arch Linux: 4.14.15-1-ARCH
Python 3.6.4
pip 9.0.1
virtualenv 15.1.0
ChromeDriver 2.35.528139
geckodriver 0.19.0