Issue #1297 - Intranet NuGet Gallery with Update from Official Source

I have added the ability to set a flag that enables the NuGet Gallery as an intranet site. This sets both branding, and the ability to update your intranet NuGet Gallery with packages directly from the official source. I think this is a feature that a lot of companies are looking for. Managed access to everything on the official source, with the ability to host internal NuGet packages.