Add PromiseKit dependency

- Added PromiseKit dependency

Carthage/Checkouts/PromiseKit/Tests/A+/2.2.7.swift

@@ -0,0 +1,33 @@
+import PromiseKit
+import XCTest
+
+class Test227: XCTestCase {
+    func test() {
+        describe("2.2.7: `then` must return a promise: `promise2 = promise1.then(onFulfilled, onRejected)") {
+            describe("2.2.7.2: If either `onFulfilled` or `onRejected` throws an exception `e`, `promise2` must be rejected with `e` as the reason.") {
+
+                testFulfilled { promise1, expectation, _ in
+                    let sentinel = arc4random()
+                    let promise2 = promise1.done { _ in throw Error.sentinel(sentinel) }
+
+                    promise2.catch {
+                        if case Error.sentinel(let x) = $0, x == sentinel {
+                            expectation.fulfill()
+                        }
+                    }
+                }
+
+                testRejected { promise1, expectation, _ in
+                    let sentinel = arc4random()
+                    let promise2 = promise1.recover { _ -> Promise<UInt32> in throw Error.sentinel(sentinel) }
+
+                    promise2.catch { error in
+                        if case Error.sentinel(let x) = error, x == sentinel {
+                            expectation.fulfill()
+                        }
+                    }
+                }
+            }
+        }
+    }
+}