When building a list of errors for `ValidationError.message`, include
the values of invalid properties too.
In order to keep the message reasonably short, the values are truncated
at approx 32 characters.
Previously validations were appended to an array when configured. The
format was cumbersome, and led to issues. This refactors the
configuration into an object, as a property of the Model.
Note that if no validations have been configured, this property is
currently `undefined`.
- change `statusCode` from 400 to 422
- nest `context` and `codes` inside `details`
- add `details.messages`
- reword the main error message
Remove the call to Error's constructor from ValidationError constructor,
because it's a no-op - Error's constructor creates a new
instance when called via `.call()`.
- Add a ModelDefinition class to encapsulate the model schema handling
- Add a Connector class as the base class for connector implementations
- Optimize attachTo and mixin
- Rename some properties/methods
Raymond Feng
Miroslav Bajtoš
Fabien Franzen
Ritchie Martori
Anatoliy Chakkaev