def run_instances(image_id, min_count, max_count, group_ids, key_name, user_data='',
addressing_type = nil, instance_type = nil,
kernel_id = nil, ramdisk_id = nil, availability_zone = nil,
block_device_mappings = nil)
launch_instances(image_id, {:min_count => min_count,
:max_count => max_count,
:user_data => user_data,
:group_ids => group_ids,
:key_name => key_name,
:instance_type => instance_type,
:addressing_type => addressing_type,
:kernel_id => kernel_id,
:ramdisk_id => ramdisk_id,
:availability_zone => availability_zone,
:block_device_mappings => block_device_mappings
})
end