Language negotiation for service and collection metadata

[jampukka]

Should solve #197

• Catalog (concept, not a class)
  • A per-language .properties file declared with locale.<lang>.path, holding
    only the keys that differ from the base config
  • Localization gets its values from here, falling back to the base config
    per key, so a catalog can be arbitrarily sparse and a declared language
    needs no catalog at all
  • LocalizableKeys describes the allowed keys a catalog file can override, extraneous keys will throw an exception
• Localization
  • Holds all localized values from catalogs, constructed at startup time as part of configuration parsing.
  • Localized value resolution is per key (catalog > base config > null), which is what makes sparse catalogs work.
• LangNegotiation
  • Contains logic for language negotiation with ?lang= and Accept-Language
• LocalizableKeys
  • Controls which properties are localizable (via configuration)
• LocalizedFeatureServiceConfig / LocalizedFeatureType
  • Wraps the Config/FeatureType, translates title/description (via Localization), delegates every other method to wrapped Config/FeatureType.

[teezip]

Thanks! Suggested configuration model, negotiation implementation and localization of descriptive elements seems to be fine.