Use CSE as prefix for QRCodes

CSE makes it clearer that it's linked to CSEntry

app/models.py

@@ -148,11 +148,11 @@ class QRCodeMixin:
         """Return a QRCode image to identify a record
 
         The QRCode includes:
-             - ICS prefix
+             - CSE prefix
              - the table name
              - the name of the record
         """
-        data = ':'.join(['ICS', self.__tablename__, self.name])
+        data = ':'.join(['CSE', self.__tablename__, self.name])
         return qrcode.make(data, version=1, box_size=5)
 
     def __str__(self):