Fix deprecations on ChefSpec >= 4.1

I was getting a ton of warnings when running chefspec.

> [DEPRECATION] `ChefSpec::Runner.define_runner_method' is deprecated. Please use `ChefSpec.define_matcher' instead. (called from spec/support/factories.rb:29:in `block in setup_node')
> "/var/folders/30/vtzm8b791v35g4v99c52jgx80000gn/T/d20141024-86388-ddr9vz/cookbooks/windows/libraries/matchers.rb:2:in `<top (required)>'"

I've tested locally, this gets rid of the warnings and also gets rid of some duplication.