Send/receive expiration times for group updates.

This particularly helps with the bug where people who were newly added
to a group wouldn't receive an expiration timer until the first message
was sent.

src/org/thoughtcrime/securesms/jobs/PushDecryptJob.java

@@ -380,9 +380,14 @@ public class PushDecryptJob extends ContextJob {
   private void handleGroupMessage(@NonNull SignalServiceEnvelope envelope,
                                   @NonNull SignalServiceDataMessage message,
                                   @NonNull Optional<Long> smsMessageId)
+      throws MmsException
   {
     GroupMessageProcessor.process(context, envelope, message, false);
 
+    if (message.getExpiresInSeconds() != 0 && message.getExpiresInSeconds() != getMessageDestination(envelope, message).getExpireMessages()) {
+      handleExpirationUpdate(envelope, message, Optional.absent());
+    }
+
     if (smsMessageId.isPresent()) {
       DatabaseFactory.getSmsDatabase(context).deleteMessage(smsMessageId.get());
     }

src/org/thoughtcrime/securesms/jobs/PushGroupSendJob.java

@@ -168,6 +168,7 @@ public class PushGroupSendJob extends PushSendJob implements InjectableType {
       SignalServiceGroup        group            = new SignalServiceGroup(type, GroupUtil.getDecodedId(groupId), groupContext.getName(), groupContext.getMembersList(), avatar);
       SignalServiceDataMessage  groupDataMessage = SignalServiceDataMessage.newBuilder()
                                                                            .withTimestamp(message.getSentTimeMillis())
+                                                                           .withExpiration(message.getRecipient().getExpireMessages())
                                                                            .asGroupMessage(group)
                                                                            .build();