patch empty message remaining

sms_counter/main.py

@@ -84,6 +84,10 @@ class SMSCounter(object):
         # and then convert the ceil result to int
         # since python 2.7 return a float
         messages = int(ceil(length / float(permessage)))
+
+        if length == 0:
+            remaining = permessage
+        else:
             remaining = (permessage * messages) - length
 
         returnset = {