Add PromiseKit dependency

- Added PromiseKit dependency

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

@@ -0,0 +1,48 @@
+# PromiseKit UIKit Extensions ![Build Status]
+
+This project adds promises to Apple’s UIKit framework.
+
+This project supports Swift 3.0, 3.1, 3.2 and 4.0; iOS 9, 10 and 11; tvOS 10 and
+11; CocoaPods and Carthage; Xcode 8.0, 8.1, 8.2, 8.3 and 9.0.
+
+## CocoaPods
+
+```ruby
+pod "PromiseKit/UIKit", "~> 6.0"
+```
+
+The extensions are built into `PromiseKit.framework` thus `import PromiseKit` is
+all that is needed.
+
+## Carthage
+
+```ruby
+github "PromiseKit/UIKit" ~> 3.0
+```
+
+The extensions are built into their own framework:
+
+```swift
+// swift
+import PromiseKit
+import PMKUIKit
+```
+
+```objc
+// objc
+@import PromiseKit;
+@import PMKUIKit;
+```
+
+# `UIImagePickerController`
+
+Due to iOS 10 requiring an entry in your app’s `Info.plist` for any usage of `UIImagePickerController` (even if you don’t actually call it directly), we have removed UIImagePickerController from the default `UIKit` pod. To use it you must add an additional subspec:
+
+```ruby
+pod "PromiseKit/UIImagePickerController"
+```
+
+Sorry, but there’s not an easier way.
+
+
+[Build Status]: https://travis-ci.org/PromiseKit/UIKit.svg?branch=master