Added support for natlog and OpenIE

[Curiousite]

It would be great to have support for the Annotators natlog and openIE. I am pretty new to open source software, but motivated to help wherever I can with the implementation.

[gerardobort]

Hi @Curiousite,

I would be happy to merge a PR if you want to contribute with that. Also, I'll review and merge #49 as soon as I can.

Thanks!

[Curiousite]

Hi @gerardobort,
thanks for the fast reply! I'll try my best to contribute. But since I am new to the subject, I might need a little help here and there. :)