'http://docs.aws.amazon.com/AutoScaling/latest/DeveloperGuide/as-scale-based-on-demand.html
If PercentChangeInCapacity returns a value between 0 and 1,
Auto Scaling will round it off to 1. If the PercentChangeInCapacity
returns a value greater than 1, Auto Scaling will round it off to the
lower value. For example, if PercentChangeInCapacity returns 12.5,
then Auto Scaling will round it off to 12.'

def change_capacity_percent(self, group_name, scaling_adjustment):

    group = self.autoscaling_groups[group_name]
    percent_change = (1 + (scaling_adjustment / 100.0))
    desired_capacity = (group.desired_capacity * percent_change)
    if (group.desired_capacity < desired_capacity < (group.desired_capacity + 1)):
        desired_capacity = (group.desired_capacity + 1)
    else:
        desired_capacity = int(desired_capacity)
    self.set_desired_capacity(group_name, desired_capacity)
