Paper.authors now returns an empty list when no authors are present, re #51

Author: erickpeirson

tethne/classes/paper.py

@@ -135,7 +135,7 @@ def authors(self):
         """
 
         if self['aulast'] is None:
-            return None
+            return []
 
         auths = [ ' '.join([ a,l ]).upper()
                      for a,l in zip (self['aulast'], self['auinit']) ]