Fix Powershell download on TLS > 1.0 only servers.

[Ilod]

Fixes #200

Checklist

• [ ] I have included examples or tests
• [ ] I have updated the change log
• [ ] I am listed in the CONTRIBUTORS file
• [x] I have cleaned up the commit history (use rebase and squash)

Changes proposed in this pull request:

• Set System.Net.ServicePointManager.SecurityProtocol to always accept Tls 1.1 and 1.2 in the powershell download script embedded in the PDBs.

[GeertvanHorrik]

Thanks for the contribution!