Merge pull request #5 from CutFlame/master

Added a Timeout property to the BasicGedcomxApi (default 10 seconds).
updating the csharp core model
updating the csharp atom model
updating the csharp fs model
Added TryGetAccessTokenWithoutAuthentication method to BasicGedcomxApi

This method fills in the Access Token received from starting an unauthenticated session.
Process described on this web page: https://familysearch.org/developers/docs/api/authentication/Access_Token_resource