Support custom methods attached to SchemaObject factory

[scotthovestadt]

Moving towards allowing the SchemaObject to replace Models in your code. To do this, need to attach methods to each class.

Example:

const Person = new SchemaObject({
  firstName: String,
  lastName: String
}, {
  methods: {
    getFullName: function() {
      return this.firstName + ' ' + this.lastName;
    }
  }
});