Re-type CachedURLResponse's userInfo to match what is exported by Foundation (#510)

Author: itaiferber

Foundation/NSURLCache.swift

@@ -90,7 +90,7 @@ open class CachedURLResponse : NSObject, NSSecureCoding, NSCopying {
         @param storagePolicy an NSURLCacheStoragePolicy constant.
         @result an initialized NSCachedURLResponse.
     */
-    public init(response: URLResponse, data: Data, userInfo: [NSObject : AnyObject]? = [:], storagePolicy: URLCache.StoragePolicy) { NSUnimplemented() }
+    public init(response: URLResponse, data: Data, userInfo: [AnyHashable : Any]? = [:], storagePolicy: URLCache.StoragePolicy) { NSUnimplemented() }
 
     /*! 
         @method response
@@ -111,7 +111,7 @@ open class CachedURLResponse : NSObject, NSSecureCoding, NSCopying {
         @abstract Returns the userInfo dictionary of the receiver. 
         @result The userInfo dictionary of the receiver. 
     */
-    open var userInfo: [NSObject : AnyObject]? { NSUnimplemented() }
+    open var userInfo: [AnyHashable : Any]? { NSUnimplemented() }
 
     /*! 
         @method storagePolicy