Ensure package url in feed uses feeds scheme.
Ensure package url in feed uses feeds scheme.

Fixes codeplex issue #2533

grenade/NuGetGallery_download-count-patch,KuduApps/NuGetGallery,mtian/SiteExtensionGallery,JetBrains/ReSharperGallery,KuduApps/NuGetGallery,skbkontur/NuGetGallery,mtian/SiteExtensionGallery,KuduApps/NuGetGallery,ScottShingler/NuGetGallery,grenade/NuGetGallery_download-count-patch,ScottShingler/NuGetGallery,projectkudu/SiteExtensionGallery,JetBrains/ReSharperGallery,skbkontur/NuGetGallery,skbkontur/NuGetGallery,JetBrains/ReSharperGallery,projectkudu/SiteExtensionGallery,grenade/NuGetGallery_download-count-patch,KuduApps/NuGetGallery,mtian/SiteExtensionGallery,KuduApps/NuGetGallery,ScottShingler/NuGetGallery,projectkudu/SiteExtensionGallery