internal: Fix caching issues with config variants. Before, changing config variant values could incorrectly re-use a previously cached config as long as there were the same number of variants. Now we build a stricter cache hash based on the actual values.

cov-core==1.15.0
coverage==4.0.3
invoke==0.12.2
mock==1.0.1
pytest==2.8.7
pytest-cov==2.2.1
pytest-mock==0.10.1