Cleanup tabs in project.json files
Use nameof when initializing `GeneratedTagHelperContext`

nits:
- missing blank line before a comment
- cleanup line breaks in `RazorPage.CreateTagHelper`
Tag Helpers: add `ModelExpression` class to support `Expression<Func<TModel, TValue>>` attributes
- includes new `RazorPage<TModel>.CreateModelExpression<TValue>()` method
- #1240

nit:
- regenerating the resources reordered Microsoft.AspNet.Mvc.Core's Resources.designer.cs
Add copyright notices to new files