Conversion of models metadata

I continued the work liddellj  started in #5.

Added a SwaggerModelData and SwaggerModelPropertyData and tried implementing the conversion using the same approach as with the SwaggerRouteData.
I wasn't sure but I tried to use use the same convention used in the SwaggerRouteData 'Operation' properties. Although in SwaggerRouteData  there might be a reason there, because some properties are non-operation prefixed.
But I totally agree and will rename them ;-)