Metaprogrammed version

I thought I'd write a meta-programmed version of the wrapper, so that when new methods are made available on the API, the wrapper doesn't need to change.

The drawback is that the parameters are now required in the method calls, e.g:
`datumbox.document_similarity(original: 'This document is unique.',
         					 copy: 'No, bastard! This document here is unique!.') `

If you like the solution, feel free to merge!

Cheers,
Pedro