Added Microsoft.AspNet.WebApi Nuget Package reference to ErrandBoy.Web.Common.

Initially got an error when I attempted to add the package using the PM Console. Posted a Question on StackOverflow => http://stackoverflow.com/q/27651342/325521

Then I tried adding using the Package Manager UI, and that worked! Not sure why PM Conole command failed... Check the Stackoverflow question http://stackoverflow.com/q/27651342/325521 if any solution has been found when you read this commit message :)
Unistalled Microsoft.AspNet.WebApi from ErrandBoy.Common Project as I had incorrectly installed it there, instead of in the ErrandBoy.Web.Common Project. Oops.
Added Microsoft.AspNet.WebApi Nuget Package reference to ErrandBoy.Web.Common.

Initially got an error when I attempted to add the package using the PM Console. Posted a Question on StackOverflow => http://stackoverflow.com/q/27651342/325521

Then I tried adding using the Package Manager UI, and that worked! Not sure why PM Conole command failed... Check the Stackoverflow question http://stackoverflow.com/q/27651342/325521 if any solution has been found when you read this commit message :)
Created ApiVersionConstraint class to implement Api Routing constraints so that the correct version of Api controller is used when Api is invoked from Api Clients.
Implemented the Match(...) method in the ApiVersionConstraint class.
Created ApiVersion1RoutePrefixAttribute class for Api Version 1 Routing.
Implemented ApiVersion1RoutePrefixAttribute class to encapsulate the 'api/v1' part of the route template so that we don’t have to copy and paste it over all of the web api controllers.
Added [ApiVersion1RoutePrefix("tasks")] attribute to the TaskController in v1 version of the Api. This is equivalent to saying [RoutePrefix("api/{apiVersion:apiVersionConstraint(v1)}/tasks")]
Implemented AddTask(..) Method in api/v1 TasksController.
Implemented AddTask(..) in api/v2 of TasksController.