FIX sale_planner Transit time calculations.

Tested in these scenarios.
 - won't ship until next week and would be delivered in the week
 - won't ship until next week and delivered the following week
 - will ship this week and deliver this week
 - will ship this week and deliver next week

sale_planner/models/delivery.py

@@ -72,12 +72,9 @@ class DeliveryCarrier(models.Model):
                 return self._calculate_transit_days_naive(date_planned, date_delivered)
             if current_date_planned == date_planned:
                 date_planned += timedelta(days=1)
+                transit_days += 1
             else:
                 date_planned = current_date_planned
-            transit_days += 1
-
-        if transit_days > 1:
-            transit_days -= 1
 
         return transit_days