Update Readme with tips on how to run unit tests in VS
Update Readme with tips on how to run unit tests in VS

As setting up my new machine, I was reminded that you need the xunit extension for VS otherwise you aren't going to see any unit tests.
JetBrains/ReSharperGallery,KuduApps/NuGetGallery,mtian/SiteExtensionGallery,projectkudu/SiteExtensionGallery,KuduApps/NuGetGallery,grenade/NuGetGallery_download-count-patch,KuduApps/NuGetGallery,skbkontur/NuGetGallery,projectkudu/SiteExtensionGallery,KuduApps/NuGetGallery,skbkontur/NuGetGallery,skbkontur/NuGetGallery,projectkudu/SiteExtensionGallery,mtian/SiteExtensionGallery,JetBrains/ReSharperGallery,grenade/NuGetGallery_download-count-patch,grenade/NuGetGallery_download-count-patch,ScottShingler/NuGetGallery,KuduApps/NuGetGallery,ScottShingler/NuGetGallery,ScottShingler/NuGetGallery,mtian/SiteExtensionGallery,JetBrains/ReSharperGallery