Removes (?) unneeded file from solution.
Breaks apart model binding from NameValuePair generation.

We had a single class MvcEncoderDecoder, which didn't really match how MVC
encodes and decodes values. Also, it would make it difficult to treat
forms and querystrings differently. So changes to MvcDecoder.
MvcQueryStringEncoding takes care of creating RouteValueDictionary from a
value.
Fixes #1, wrong decoding of form/querystring values.

Uses more natural MVC mechanisms to decode the querystring, and also the
submitted form. Forms now get decoded via FormValueProvider,
JsonValueProvider and HttpFileCollectionValueProvider (for uploaded
files).