issue with printing offer

[Sirorezka]

class Offer(object) in trade.py have error in __repr__ method:

• currency should be '%s'
• final_quantity doesn't print when None
• status_round doesn't print with None
• space between '%' and 'f': final_quantity: % f

My suggestion for fixing above would be:

    def __repr__(self):
        i_fin_quant = str(self.final_quantity)
        i_status_round = str(self.status_round)

        return ("""<{sender: %s, receiver: %s, good: %s, quantity: %f, price: %f, currency: %s,
                sell: %s, status: %s, final_quantity: %s, id: %i, made: %s, status_round: %s }>""" %
                (self.sender, self.receiver, self.good, self.quantity, self.price, self.currency,
                self.sell, self.status, i_fin_quant, self.id, self.made, i_status_round))