Fix error caused by legacy configuration with multiple stack files

Print Salt version number and test suite name when running tests
Clean up duplicate code in .kitchen.yml
Update rubyzip version to 1.2.2
Add tests for upcoming Fluorine release
Add tests for v2016.11.10, v2017.7.8, and v2018.3.3

Add documentation on pillar chaining

Add tests for Salt v2017.7.7
Support multiple stack configuration files provided as a list

Address a Salt API change in versions 2017.7.5 and 2018.3.1

Add tests for specific minor versions of Salt
Update Gem bundle for Kitchen testing

Add support for a new configuration format

Allow configuration for multiple Git repositories
Add support for kitchen testing