Include Sitecore.Ship.zip in the generated NuGet package

[patrickperrone]

Hi Kevin. I'm a big fan of Sitecore.Ship. I've recently written a PowerShell script to install your tool onto a Sitecore instance by downloading the package from a NuGet feed. I'd like to support installing Sitecore.Ship's Sitecore content as well. If you include the .zip package in the tools folder, for example, I can modify my script to install Sitecore.Ship then use Sitecore.Ship to install the .zip file. :)

installer can be found here: https://github.com/patrickperrone/Sitecore.Ship-PowerShell-Installer