Close #17: Validate required_features
validate origin
added describe per property
more updates to origin validation
formatting cleanup
Close #12: validate messages
remove required_features from comments
quote cleanup
Issue #10: Validate `inputs`

* Add `inputs` to schema

* Big rework of validation recursion

* Flattened and merged some loops into top level validator

* Support for `additionalProperties` in schema validation

* Change error message for minLength on strings

* Misc refactorings and tests
Merge pull request #21 from lmorchard/10-inputs

Issue #10: Validate `inputs`
changed error output to string
fixed quotes
test fixes and more cleanup
Close #11: Validate permissions

* Validate `permissions`

* Support for `patternPermissions` schema

* Rework how `additionalProperties` is handled

* Use "Item" instead of a number for consistent error keys resulting from arrays

* Tests