Fix last seen edge case

Author: hamishcoleman

scripts/n2n-ctl

@@ -174,6 +174,10 @@ def str_table(rows, columns, orderby):
 
 def num2timestr(seconds):
     """Convert a number of seconds into a human time"""
+
+    if seconds == 0:
+        return "now"
+
     days, seconds = divmod(seconds, (60*60*24))
     hours, seconds = divmod(seconds, (60*60))
     minutes, seconds = divmod(seconds, 60)