Edited Issue: Allow Preinstalled Packages to come from multiple respositories [2941]

When custom project templates are created, developers often want to build upon existing project templates that shipped in the box. When applying preinstalled packages with templates, these developers should be able to indicate that some packages come from the existing ASP.NET template packages, while adding more packages into the list. This requires that preinstalled packages come from multiple repositories.

Presently, all preinstalled packages must come from the same repository.