Add spec for whereURL
Update API to use indexURL & showURL
Fix URL parameterization for MongoDB primary keys
Release v0.4.1
Add ability to set properties via the following methods:

	instance.string('propertyName');
	instance.number('propertyName');
	instance.integer('propertyName');
	instance.boolean('propertyName');

These methods add validations and set properties when the model is instantiated.
Update README
Release v0.4.2
Add computed property spec
Add computed property mock
Add computed properties to model:

	function TShirt() {
      this.number('price');
      this.computedProperty('salePrice', function() {
        return this.price - (this.price * 0.2);
      }, 'price');
    });
Update README to add computed properties
Expound on computed properties in README
Release v0.4.3
Fix indentation error in README