Add support for post body and oauth body hash

[westonkd]

[coveralls]

Coverage remained the same at 100.0% when pulling 10df50cadbd7b094abcb982cf9d21854d3b275d7 on westonkd:master into 4a375da4e213667e356e98a9e2bc3c3b8b969d67 on laserlemon:master.

[notEthan]

@westonkd this repo has been dead for some years, I would advocate my own library OAuthenticator https://github.com/notEthan/oauthenticator