Updated the NuGet client to the current version.

[ccellar]

Restoring of xunit.runner.console 2.1.0 failed with the following message.

The 'xunit.runner.console 2.1.0' package requires NuGet client version '2.8.1' or above, but the current NuGet version is '2.7.41115.310'.
Task failed with Package installation of C:\Projekte\Git\fake-xrm-easy\FakeXrmEasy.Tests\packages.config generation failed.

This will lead to a failing build. Could be tested with a clean build.

[jordimontana82]

Thanks a mill Christoph!

[jordimontana82]

Hi @ccellar

Just added the older client too, cause it was failing during the NuGet publish from the FAKE script, and it looks like it won't be fixed until Nuget 3.5 Beta2 so...

fsprojects/FAKE#1241

NuGet/Home#2653