[SSK] Don't mark messages as failed prematurely

Previously we were marking on first failure, meaning we might still be
retrying, but we only want to mark as failed after we've stopped
retrying (or if it's a non-retryable failure).

// FREEBIE

Podfile.lock

@@ -132,7 +132,7 @@ CHECKOUT OPTIONS:
     :commit: 139bde37738ccb6ebcc68bf1b02c8a28400b6760
     :git: https://github.com/WhisperSystems/SignalProtocolKit.git
   SignalServiceKit:
-    :commit: 19d8a32022187932d5b5ad22039de54bbca1bdaf
+    :commit: d4e0c49ff98f88ea053b3c4875b81270a8ab8ea0
     :git: https://github.com/WhisperSystems/SignalServiceKit.git
   SocketRocket:
     :commit: 877ac7438be3ad0b45ef5ca3969574e4b97112bf