updating the page generator and base view to work with razor helper functions

@NTaylorMullen 
WriteAttribute gets called. It's also in the generated code (ex. https://github.com/aspnet/Diagnostics/blob/dev/src/Microsoft.AspNet.Diagnostics/Views/WelcomePage.cs#L29) and WrtieAttributeTo gets called from the helper functions (https://github.com/aspnet/Diagnostics/blob/elm/src/Microsoft.AspNet.Diagnostics.Elm/Views/LogPage.cs#L78)