Install Prerelease modules with PSModule DSC Resource

[FISHMANPET]

I see a few DSC specific issues have been copied here even though none of the DSC resource code has moved to this repo, so I assume this is where DSC resource related issues go, and that they will eventually be moved over before the re-write is "done."

Currently the PSModule resource doesn't allow Prerelease modules, because it doesn't include support for the -AllowPrerelease flag. Without it, it's not possible to use the PSModule resource to install a Prerelease module.

[alerickson]

Hi @FISHMANPET I'll move the DSCResources over to this repo so updates and bug fixes for that can properly addressed here

[brwilkinson]

+1 for allowprerelease.

at least for PowerShellGet 3.0.0.0

[StevenBucher98]

Moving to new PSGetDSC repo: https://github.com/PowerShell/PowerShellGetDsc