Implement Action "to" as Expressions of ressource rather than string

[tjaskula]

Today in order to define ressource templates matching methods, URI and action we use strings everywhere like that

Action(6, "PUT", "/users/{userId}", "changeUser(string userId, body:Vlingo.Http.Tests.Sample.User.UserData userData)", "Vlingo.Http.Tests.Sample.User.UserDataMapper");

It would be much nicer instead of using magic string "changeUser(string userId, body:Vlingo.Http.Tests.Sample.User.UserData userData)" to use the expression tree

(resource, userId, userData) => resource.ChangeUser(userId, userData)

We could also replace magic string "PUT" by an enum