Modifying ViewDataDictionary and RouteValueDictionary to copy on write
instead of eagerly copying.

Partial fix for #878
NoContentFormatter: Writes 204 to the response status code if the value returned is null.
Removed source files from the project
Fixing build break due to tests
Moving Input formatters to use HeaderValueAbstractions
Adding Input Formatters to MVC Options.
Adding the input descriptors and addressing the feedback.
Adding a functional test.
Removing a file