moved magic unpublish date to static (code review #46)
moved magic unpublish date to static (code review #46)

projectkudu/SiteExtensionGallery,kudustress/NuGetGalleryOptmized,JetBrains/ReSharperGallery,kudustress/NuGetGalleryOptmized,projectkudu/SiteExtensionGallery,kudustress/NuGetGallery2,ScottShingler/NuGetGallery,kudustress/NuGetGallery2,KuduApps/NuGetGallery,projectkudu/SiteExtensionGallery,KuduApps/NuGetGallery,mtian/SiteExtensionGallery,JetBrains/ReSharperGallery,KuduApps/NugetGallery16Fx45-DeleteMe,ScottShingler/NuGetGallery,skbkontur/NuGetGallery,mtian/SiteExtensionGallery,mtian/SiteExtensionGallery,kudustress/NuGetGallery,KuduApps/NuGetGallery,KuduApps/NugetGallery21Fx45-DeleteMe,skbkontur/NuGetGallery,grenade/NuGetGallery_download-count-patch,skbkontur/NuGetGallery,kudustress/NuGetGallery,JetBrains/ReSharperGallery,KuduApps/NuGetGallery,grenade/NuGetGallery_download-count-patch,KuduApps/NugetGallery21Fx45-DeleteMe,KuduApps/NuGetGallery,grenade/NuGetGallery_download-count-patch,KuduApps/NugetGallery16Fx45-DeleteMe,ScottShingler/NuGetGallery