Hi Forks,

I notice when use docker-machine to launch machine in AWS China the endpoint is not right, the error message is:

'''client encountered error while doing the request: Get https://ec2.cn-north-1.amazonaws.com/?Action=DescribeKeyPairs&Version=2014-06-15: dial tcp: lookup ec2.cn-north-1.amazonaws.com: no such hostError creating machine: Problem with AWS API call: client encountered error while doing the request: Get https://ec2.cn-north-1.amazonaws.com/?Action=DescribeKeyPairs&Version=2014-06-15: dial tcp: lookup ec2.cn-north-1.amazonaws.com: no such host
You will want to check the provider to make sure the machine and associated resources were properly removed.
'''
The docker-machine version I used:
docker-machine version 0.3.0 (0a251fe)

From our experience on AWS China, the AWS China is an a Isolated region and the endpoint is:
ec2.cn-north-1.amazonaws.com.cn
not the same pattern with other AWS region https://ec2.%s.amazonaws.com

You can reproduce this issue by using docker-machine to launch instances inside AWS China, if needed, I can provide a temp AWS China credential,

The same issue report by @xiaoluffy with #1224 before on version 0.2.0 , also ping @ehazlett

I am guessing need someone help on the NewEC2 function on this file:
https://github.com/docker/machine/blob/ff4650b9ed7ed145e70de4378cf729e8df6e3a5a/drivers/amazonec2/amz/ec2.go

Thanks!