Avoid NREs in MVC sample
- see e.g. results of `GET ~/Home/Post`
- use parentheses to avoid `?` confusing Razor

nit: remove unused Home/Test.cshtml view
Extend MVC Sample functional test to include all Home views
Touch up tag helper sample
- provide list of users on Index page
 - currently uses only the `<a/>` helper but left `<label/>` and `<input/>` comments
- get date picker working on Create and Edit pages
 - add `[DataType]` annotation
 - use format browsers recognize

nits:
- move "Create New" link to the bottom of `~/Home/Index`
- correct code comment about assigning to a `ViewBag` property