Deprecate old requestFor function and make new one (using URLRequest as

the return value) the recommended one, but with only the channel name, 
instead of the whole channel object, passed in as a parameter.

Author: hamchapman

Source/PusherClientOptions.swift

@@ -19,7 +19,10 @@ public enum PusherHost {
 }
 
 @objc public protocol AuthRequestBuilderProtocol {
-    func requestFor(socketID: String, channel: PusherChannel) -> URLRequest?
+    @available(*, deprecated: 4.0.2, message: "use requestFor(socketID: String, channelName: String) -> URLRequest? instead")
+    @objc optional func requestFor(socketID: String, channel: PusherChannel) -> NSMutableURLRequest?
+
+    @objc optional func requestFor(socketID: String, channelName: String) -> URLRequest?
 }
 
 public enum AuthMethod {

Source/PusherConnection.swift

@@ -523,7 +523,11 @@ open class PusherConnection: NSObject {
                         return true
 
                     case .authRequestBuilder(authRequestBuilder: let builder):
-                        if let request = builder.requestFor(socketID: socketID, channel: channel) {
+                        if let request = builder.requestFor?(socketID: socketID, channel: channel) {
+                            sendAuthorisationRequest(request: request as URLRequest, channel: channel, callback: callback)
+
+                            return true
+                        } else if let request = builder.requestFor?(socketID: socketID, channelName: channel.name) {
                             sendAuthorisationRequest(request: request, channel: channel, callback: callback)
 
                             return true