Use multi_json rather than a hacky implementation of swappable json backends.
Extract stateless helper methods for version and metaschema.
Add a method just to fully validate the schema itself.
Pulling multi_json directly into the library.
Removing the MultiJSON vendored lib and making it auto-load if available; otherwise, the old JSON-backend strategy is used. This removes the dependency to MultiJSON, but uses it if available.
Update README and VERSION to reflect the MultiJSON stuff.
Fixing fully_validate for union types and adding a :errors_as_objects option to fully_validate to return errors as hash objects instead of strings.
For some reason 'extends' wasn't allowing referencing of schemas by URI.
Added tests for nested property validation. Currently fails.
Fixed tests after feedback from khoxworth. Impl works fine,  my schema was
wrong. :P
change Validator#initialize_data to only parse json or read from a URI when told to. add methods validate_json, validate_uri, and their full and bang counterparts to tell it to.
add test for validate_json
add a bunch of tests where the root data object is of various types - especially string, as this is what was problematic before.
Fix deprecation warning on newer MultiJson versions
Updated remaining usages of MultiJson to work with new & old APIs
Allow optional decimal fraction for seconds in date-time format validation.
date-time format should accept times with fractional seconds part (with either comma or dot as separator)
accept fractional second parts with either comma or dot (and do it right!)
The base validator method should act as it previously did when not accompanied with a :uri or :json option
Merge remote branch 'japgolly/multi_json_fix' into merge-vapir