minor: rename app settings config supplier provider method name
core: make auto compile fs events coalesce period configurable

by system property as it was before refactoring
core: config: add getBoolean accessor + make empty values return Optional.absent
core: refactor: use config rather than system property for main router factory settings nad restx.mode
spec: refactor: spec storage settings are now provided as settings
config: properly mark origin of system properties and ensure they have strongest priority