Make task delay a configurable setting.

mayan/apps/common/settings.py

@@ -35,3 +35,11 @@ setting_auto_logging = namespace.add_setting(
         'Automatically enable logging to all apps.'
     )
 )
+settings_db_sync_task_delay = namespace.add_setting(
+    global_name='COMMON_DB_SYNC_TASK_DELAY',
+    default=2,
+    help_text=_(
+        'Time to delay background task that depend on a database commit to '
+        'propagate'
+    )
+)

mayan/apps/ocr/apps.py

@@ -13,6 +13,7 @@ from common import (
     MayanAppConfig, menu_facet, menu_multi_item, menu_object, menu_secondary,
     menu_tools
 )
+from common.settings import settings_db_sync_task_delay
 from documents.models import Document, DocumentType, DocumentVersion
 from documents.search import document_search
 from documents.signals import post_version_upload
@@ -45,7 +46,8 @@ def document_ocr_submit(self):
 
 def document_version_ocr_submit(self):
     task_do_ocr.apply_async(
-        kwargs={'document_version_pk': self.pk}, countdown=1
+        kwargs={'document_version_pk': self.pk},
+        countdown=settings_db_sync_task_delay.value
     )