Use a parameterised class, for hiera config-ability

The specs were already broken by #5, this also fixes those.

`scripts/syntax` is broken, though, and just dumps straight back to the
shell. NFI.
Upgrade cardboard and dependencies

Should fix broken specs
Add a default clause, to satisfy the linter
Merge pull request #7 from boxen/parameterise

Parameterise the top-level Riak class