Add group chat authorization endpoint

Signal/src/ViewControllers/Registration/OnboardingController.swift

@@ -152,7 +152,7 @@ public class OnboardingController: NSObject {
         // from the "code verification" view.  The "Captcha" view should always appear
         // immediately after the "phone number" view.
         while navigationController.viewControllers.count > 1 &&
-            !(navigationController.topViewController is OnboardingAccountDetailsViewController) {
+            !(navigationController.topViewController is AccountDetailsViewController) {
                 navigationController.popViewController(animated: false)
         }
 

SignalServiceKit/src/Loki/API/LokiGroupChatAPI.swift

@@ -18,7 +18,18 @@ public final class LokiGroupChatAPI : NSObject {
     }
     
     public enum Error : Swift.Error {
-        case messageParsingFailed
+        case tokenParsingFailed, messageParsingFailed
+    }
+    
+    public static func getEncryptedToken() -> Promise<String> {
+        print("[Loki] Getting group chat auth token.")
+        let url = URL(string: "\(serverURL)/loki/v1/getToken")!
+        let parameters = [ "pubKey" : userHexEncodedPublicKey ]
+        let request = TSRequest(url: url, method: "POST", parameters: parameters)
+        return TSNetworkManager.shared().makePromise(request: request).map { $0.responseObject }.map { rawResponse in
+            guard let json = rawResponse as? JSON, let encryptedToken = json["cipherText64"] as? String else { throw Error.tokenParsingFailed }
+            return encryptedToken
+        }
     }
     
     public static func getMessages(for group: UInt) -> Promise<[LokiGroupMessage]> {