try to adjust the copyright file so lintian is happy

debian/copyright

@@ -10,9 +10,7 @@ https://labs.riseup.net/code/repositories/show/backupninja
 backupninja was originally written by elijah@riseup.net, for a full list of
 authors see AUTHORS.
 
-Copyright:
-
-   Copyright (C) Riseup Networks
+Copyright (C) 2004-2010 Riseup Networks
    
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by