Added SDK9 project

[estpla]

Hi,
I made an SDK9 project for your library.

[kind-serge]

Thanks @estpla, do you know if SDK9 introduces any new features? I think you should be able to use XRM v9 and this project v8 together without need for an update.

[estpla]

I'm not totally sure about the new features. But, if you use v8 to connect to a CRM in version 9.0, it gives a connection error. Seems to be a problem with TLS 1.2. This error gets corrected with .NET Framework 4.6 and above.

Some links with info:
https://community.dynamics.com/crm/b/abhinavranjandynamics365/archive/2018/01/31/follow-up-on-tls-1-2-issue-in-dynamics-365
https://community.dynamics.com/crm/b/mrdavesdavidyackdynamicscrmblog/archive/2018/01/08/tls-1-0-and-1-0-now-blocked-to-dynamics-365-9-0-orgs

I guess that in my pull request, we should change .NET 4.6.1 framework by 4.6.