Adds creation timestamp and failure URL to __str__ method in BoletaErrorMessage class

[fsologureng]

Reports from system about API ventas errors doesn't contain date nor failed request's url

ecommerce/ecommerce/extensions/payment/models.py

Lines 379 to 390 in 95700b8

	class BoletaErrorMessage(models.Model):
	"""
	The messages are processed by other clases and then disposed off.
	Normally there should be no messages as they would be sent by email.
	"""
	code = models.PositiveSmallIntegerField(default=0)
	order_number = models.CharField(max_length=20,default="")
	content = models.CharField(max_length=255)
	error_at = models.DateTimeField(default=timezone.now)
	def __str__(self):
	return "Unsent message with code {}, check the email settings".format(self.code)

The URL must be passed from constructor where request data is available.