* Porting Hidden and HiddenFor unit tests

Partial fix to #453
please add the following to this data set:
``` c#
  var localVariable = "local-value";
  ...
    {
      model => localVariable,
      @"<input data-val=""true"" id=""localVariable"" name=""localVariable"" " +
      @"type=""hidden"" value=""local-value"" />"
    },
```
can do more complicated expressions with a complex local variable or any accessible instance or static field or property. but probably enough to show one lambda that doesn't use "model" on the RHS.