Use 'camelize' instead of 'capitalize' in InstanceKeys#base_class_or_name

Camelize properly handles underscored names. E.G. 'example_model' becomes 'ExampleModel' instead of 'Example_model'.
Merge pull request #51 from bkudria/master

Use 'camelize' instead of 'capitalize' in InstanceKeys#base_class_or_name