Add a getOptions method to Wrapper

[alexjoverm]

As discussed on #34, the idea of having a getOptions method came up, in the same line than #27 for getAttributes and getProps. This would be an abstraction to access the wrapper.vm.$options internal variable. One of the use cases is to test property validation specs, but there might be others.

What notation to use?

1. Concise: .options(), attributes(), props()...
2. Verbose .getOptions(), getAttributes(), getProps()...

Let's discuss it

[eddyerburgh]

My feelings on this is that we shouldn't add too many aliases. I don't think this a common use case, like props or attributes, and it's not much more code to access the $options object on the vm:

wrapper.vm.$options
wrapper.options()