Pass MessageFormatters the request object when parsing to Request,
closes #33
Also null checking on request member checking.
Deleted GenericFormatter impl as it is no part of the gitdemo app
Extend GitHubFunctionProvider to handle GET requests
Modify Endpoint url pattern to match paths with added pathinfo for GETs.
refs #30
Added GetFormatter implementation, forgot to earlier.
refs #41
Added `toString` method to MessagePart for easy debugging, printing.