Add definition with test for when.settle, add a test for when.all

when/when.d.ts

@@ -101,6 +101,32 @@ declare module When {
      */
     function all<T>(promisesOrValues: any[]): Promise<T>;
 
+    /**
+     * Describes the status of a promise.
+     * state may be one of:
+     * "fulfilled" - the promise has resolved
+     * "pending" - the promise is still pending to resolve/reject
+     * "rejected" - the promise has rejected
+     */
+    interface Descriptor<T> {
+        state: string;
+        value?: T;
+        reason?: any;
+    }
+
+    /**
+     * Returns a promise for an array containing the same number of elements as the input array.
+     * Each element is a descriptor object describing of the outcome of the corresponding element in the input.
+     * The returned promise will only reject if array itself is a rejected promise. Otherwise,
+     * it will always fulfill with an array of descriptors. This is in contrast to when.all,
+     * which will reject if any element of array rejects.
+     * @memberOf when
+     *
+     * @param promisesOrValues array of anything, may contain a mix
+     *      of {@link Promise}s and values
+     */
+    function settle<T>(promisesOrValues: any[]): Promise<Descriptor<T>[]>;
+
     /**
      * Creates a {promise, resolver} pair, either or both of which
      * may be given out safely to consumers.