Cannot install Chocolatey / .NET without Windows Updates

[dylanmei]

Original issue: packer-community/packer-windows-plugins#56

1. Chocolatey can't be installed with the "elevated" directives anymore
2. .NET can't be installed without the "elevated" directives
3. Chocolatey wants to install .NET if it's not been installed by something else

The "elevated" directives run scripts via Windows Scheduled Tasks. This fails in the newer, better Chocolatey here: https://github.com/chocolatey/choco/blob/9775c21e82ad9676d8f7c33a4322eb053ea3b443/nuget/chocolatey/tools/chocolateysetup.psm1#L172-L189

Workaround is to always run Windows Updates and not install Chocolatey with the "elevated" directives.