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.

sudo: false
language: python
python:
  - "3.4"
  - "3.5"
install:
  - "python setup.py version -f 2.0"
  - "python setup.py sdist --formats=zip"
  - "pip install dist/PieCrust-2.0.zip"
script:
  - "py.test"