Extra parameters as object keys #12

It'd would be great to have a way to add additional parameters as keys. Paystack's API endpoints have lots of parameters that are not added here.
As of now, a pull request or feature request is needed in order to make it available in the code.
I'm from Ghana and lots of extra stuffs have been added to some endpoints like the mobile money feature.
It'll be a pain to always have to add small little thing when it's needed.