use string template for interpolation

ocrloader.py

@@ -9,6 +9,7 @@ import imaplib
 import os
 import os.path
 import requests
+import string
 import sys
 import tempfile
 import time
@@ -53,7 +54,9 @@ def process(cfg, filename, payload, enable_ocr=True):
     else:
         print '  uploading file'
         now = datetime.datetime.now()
-        title = cfg.get('title') % {'date': now.strftime('%d/%m/%Y'), 'time': now.strftime('%H:%M')}
+        title = string.Template(cfg.get('title')).substitute(
+                {'date': now.strftime('%d/%m/%Y'),
+                 'time': now.strftime('%H:%M')})
         t = os.system('curl -v --insecure -X POST '\
                   '--form "form.widgets.file=@%s;filename=%s;type=application/pdf" '\
                   '-F "form.buttons.import=Import" '\