Merge source code from aspnet/Identity

.gitmodules

build/buildorder.props

build/submodules.props

modules/Identity

src/Identity/.gitignore

src/Identity/Directory.Build.props

src/Identity/Directory.Build.targets

src/Identity/Identity.sln

src/Identity/IdentityCore.sln

src/Identity/NuGetPackageVerifier.json

src/Identity/README.md

src/Identity/build/Key.snk

src/Identity/build/dependencies.props

src/Identity/build/repo.props

src/Identity/build/repo.targets

src/Identity/build/sources.props

...efaultUI/Areas/Identity/Pages/Account/Manage/Index.cshtml

...ultUI/Areas/Identity/Pages/Account/Manage/Index.cshtml.cs

...le.DefaultUI/Areas/Identity/Pages/Account/Register.cshtml

...DefaultUI/Areas/Identity/Pages/Account/Register.cshtml.cs