[SSK] Better debugging information

- explicitly log type of received message vs. just "encrypted message"
  for better call debugging
- debug tool to print signed prekey report

// FREEBIE

Podfile.lock

@@ -138,7 +138,7 @@ CHECKOUT OPTIONS:
     :commit: 7054e4b13ee5bcd6d524adb6dc9a726e8c466308
     :git: https://github.com/WhisperSystems/JSQMessagesViewController.git
   SignalServiceKit:
-    :commit: cc055f034ae45dc5122e6e143b01bed4e4a46f80
+    :commit: 608852898a58d3cc3d5e8ceee27b139a5d82fc1a
     :git: https://github.com/WhisperSystems/SignalServiceKit.git
   SocketRocket:
     :commit: 877ac7438be3ad0b45ef5ca3969574e4b97112bf