New load method

[hmleal]

With the current API, I think it's too hard to serialize an object to JSON or the errors of this object. This is why I think it would be nice to have a new method called load. I think it should work like that:

Actual scenario (trying to return a JSON of the data or errors)

class Person(Model):
  name = StringType(required=True)

data = Person({})
try:
  data.validate()
  return json.dumps(data.serialize())
except Exception as e:
  return json.dumps(e.to_primitive())

If you want to use this in API it will be much more interest something like this:

Proposal

class Person(Model):
  name = StringType(required=True)

obj, errors = Person().load({})

if errors:
  return json.dumps(errors)
return json.dumps(obj.serialize())