Add hound config
Enforce 1.8 hash syntax
Actually enforce 1.8 hash syntax
Add strict_prompts option

This adds a `strict_prompts` key to the `liftoffrc` and a
`--[no]-strict-prompts` command line flag.

Enabling this option causes Liftoff to skip the prompt for keys that
already have a default value.
Update man pages for new command line options
Refactor ConfigurationParser specs

- Add test for passing in CLI options
- Rework the tests to not stub the SUT
- Don't use `let` because Caleb hates it.