Fixed unit tests failing

Author: Brandon Shega

Tests/AuthenticationTests.swift

@@ -250,7 +250,7 @@ class AuthenticationTests: XCTestCase {
     func testAuthorizationUsingSomethingConformingToTheAuthorizerProtocol() {
 
         class SomeAuthorizer: Authorizer {
-            func fetchAuthValue(socketID: String, channelName: String, completionHandler: (PusherAuth?) -> ()) {
+            func fetchAuthValue(socketID: String, channelName: String, completionHandler: @escaping (PusherAuth?) -> ()) {
                 completionHandler(PusherAuth(auth: "testKey123:authorizerblah123"))
             }
         }
@@ -280,7 +280,7 @@ class AuthenticationTests: XCTestCase {
     func testAuthorizationOfPresenceChannelSubscriptionUsingSomethingConformingToTheAuthorizerProtocol() {
 
         class SomeAuthorizer: Authorizer {
-            func fetchAuthValue(socketID: String, channelName: String, completionHandler: (PusherAuth?) -> ()) {
+            func fetchAuthValue(socketID: String, channelName: String, completionHandler: @escaping (PusherAuth?) -> ()) {
                 completionHandler(PusherAuth(
                     auth: "testKey123:authorizerblah1234",
                     channelData: "{\"user_id\":\"777\", \"user_info\":{\"twitter\":\"hamchapman\"}}"