Fix error from different compensation prediction and result

Compensation prediction doesn't persist rows into database, thus the
values that Provision provided weren't rounded at all: their excess
digits were just chopped off.
E.g. a value 1.006 from Provision calculation would be persisted as 1.01
in database, but predicition would've had a value of 1.00.

kirppu/models.py

@@ -37,7 +37,9 @@
 
 
 def decimal_to_transport(value):
-    return int(value * Item.FRACTION)
+    # round(): Database provides a rounded value anyway, so use the same
+    # to avoid having different value for database-rows and in-memory-rows (provision pre-calculation).
+    return int(round(value * Item.FRACTION))
 
 
 class UserAdapterBase(object):