updating the changes file with a couple of patches

Author: rouilj

CHANGES.txt

@@ -24,7 +24,10 @@ Fixed
   behaviour of ignoring a Resent-From:-header and using the real 
   From-header instead: new configuration option EMAIL_KEEP_REAL_FROM 
   (Peter Funk aka Pefu).
-
+- issue2550717: Changed a couple of residual email references into
+  e-mail in German translation (John Rouillard)
+- issue2550669: Adding documentation for csv_field_size to the
+  customizing tracker section of doc/customizing.txt
 
 2016-01-11: 1.5.1