Switch to GCM CCS and add support for APN feedback processing.

src/main/java/org/whispersystems/textsecuregcm/entities/EncryptedOutgoingMessage.java

@@ -55,10 +55,6 @@ public class EncryptedOutgoingMessage {
     this.serialized = Base64.encodeBytes(ciphertext);
   }
 
-  public EncryptedOutgoingMessage(String serialized) {
-    this.serialized = serialized;
-  }
-
   public String serialize() {
     return serialized;
   }