Add PromiseKit dependency

- Added PromiseKit dependency

Carthage/Checkouts/PromiseKit/Extensions/Alamofire/README.markdown

@@ -0,0 +1,93 @@
+# PromiseKit Alamofire Extensions ![Build Status]
+
+This project adds promises to [Alamofire](https://github.com/Alamofire/Alamofire).
+
+This project supports Swift 3.1, 3.2, 4.0 and 4.1.
+
+## Usage
+
+```swift
+Alamofire.request("https://httpbin.org/get", method: .GET)
+    .responseJSON().then { json, rsp in
+        // 
+    }.catch{ error in
+        //…
+    }
+```
+
+Of course, the whole point in promises is composability, so:
+
+```swift
+func login() -> Promise<User> {
+    let q = DispatchQueue.global()
+    UIApplication.shared.isNetworkActivityIndicatorVisible = true
+
+    return firstly { in
+        Alamofire.request(url, method: .get).responseData()
+    }.map(on: q) { data, rsp in
+        convertToUser(data)
+    }.ensure {
+        UIApplication.shared.isNetworkActivityIndicatorVisible = false
+    }
+}
+
+firstly {
+    login()
+}.done { user in
+    //…
+}.catch { error in
+   UIAlertController(/*…*/).show() 
+}
+```
+
+## CococaPods
+
+```ruby
+# Podfile
+pod 'PromiseKit/Alamofire', '~> 6.0'
+```
+
+```swift
+// `.swift` files
+import PromiseKit
+import Alamofire
+```
+
+```objc
+// `.m files`
+@import PromiseKit;
+@import Alamofire;
+```
+
+## Carthage
+
+```ruby
+github "PromiseKit/Alamofire-" ~> 3.0
+```
+
+The extensions are built into their own framework:
+
+```swift
+// `.swift` files
+import PromiseKit
+import PMKAlamofire
+```
+
+```objc
+// `.m files`
+@import PromiseKit;
+@import PMKAlamofire;
+```
+
+## SwiftPM
+
+```swift
+let package = Package(
+    dependencies: [
+        .Target(url: "https://github.com/PromiseKit/Alamofire", majorVersion: 3)
+    ]
+)
+```
+
+
+[Build Status]: https://travis-ci.org/PromiseKit/Alamofire.svg?branch=master