Add delay before setting etherpad content

With this delay the users browser should open and create the pad before
we try to set its content. With etherpad 1.8, setting the content fails
if the pad isn't created first.

tasks.py

@@ -5,6 +5,7 @@ import subprocess
 import shutil
 import tempfile
 from datetime import datetime
+import time
 import traceback
 from copy import copy
 import xmlrpc.client
@@ -952,7 +953,9 @@ def push_tops_to_calendar_async(protocol_id):
 
 
 def set_etherpad_content(protocol):
-    set_etherpad_content_async.delay(protocol.id)
+    # wait for the users browser to open the etherpad
+    # and for etherpad to create it, otherwise the import will fail
+    set_etherpad_content_async.apply_async((protocol.id,), countdown=10)
 
 
 @celery.task