UriPathExtensionMapping now optional, added optional QueryStringMapping

Made UriPathExtensionMapping optional
Added QueryStringMapping allowing you to add ?format=jsonp to every request in order to receive a jsonp response.
Made it after realizing there have been some changes to Chrome, sometimes sending a global (*/*) 'accepts' header on cross domain requests (<script/>), maybe some security 'improvement'.
Merge branch 'patch-1' of https://github.com/y0gzah/WebApiContrib.Formatting.Jsonp into patch-1

Conflicts:
	src/WebApiContrib.Formatting.Jsonp/JsonpMediaTypeFormatter.cs
Add in a sample case for retrieving simple JSON.
Merge branch 'patch-1'
Work on fix for problem with supporting JSON and JSONP from same API.