Support for resumable iterative function in MethodDecl

[msdvoits]

let ``Use resumable iterative method in a 'work' monad``() =
        let g = work {
            let! func    = makeValue (fun (x:float) -> x*x - 4.*x + 2.)
            let! settings= makeValue (3.0, 0.1, 0.001)
            let! root    = root (func, settings)
            return! incf root
        } 
        match eval(g) |> Async.RunSynchronously with
        | EvaluationResult.Failed  _ -> Assert.Fail("Failed to execute a work")
        | EvaluationResult.Success(v) -> Assert.AreEqual(1. + (2. + sqrt(2.)), v, 0.01, "Incorrect root")