Fix patch-04-38

The column type for quantity_decreased wasn't specified.

Change-Id: I0068c585159bfd27a12ac3076e0444b0053e65ca
Ignore cancelled payments when calling client.can_purchase

Cancelled payments should not count for the total validated on
client.can_purchase.

Change-Id: I4eea7dcbc252c7f9c3b4ddefcdf629f2d38bd662
Fixes: http://bugs.async.com.br/show_bug.cgi?id=5592