Add share_file()


 Upload files to a room. Really want this functionality - you may want to re-factor to clean up, so I've kept it simple. I've had to pull in a few dependencies, have mostly ignored error handling, and also use 'private' _url() method.
What do you think about this: https://github.com/ironcamel/WebService-Client/pull/3/files ?
I think that would allow you to do what you want, just pass in the content_type for this request.