Prefer using zeus spec over zeus rake spec

Zeus appears to keep rake in the development environment, unlike zeus
spec which runs in the test environment.
Merge pull request #78 from dgtized/prefer-zeus-spec

Prefer using zeus spec over zeus rake spec
Remove outdated test file
Remove ignore lines that should be in user .gitignores
Add a Cask file
Ignore .cask directory
Slightly refactor Makefile with cask
Ignore build artifacts
Use syntax highlighting of GFM