Terraform-provider-aws: Support adding CIDRs to existing VPC

[atsushi-ishibashi]

AWS release documentation is below.
https://aws.amazon.com/jp/about-aws/whats-new/2017/08/amazon-virtual-private-cloud-vpc-now-allows-customers-to-expand-their-existing-vpcs/

I'm looking for api documentation...

[bentterp]

https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_AssociateVpcCidrBlock.html

[atsushi-ishibashi]

Thank you!
I'll send PR👍

[sfrode]

@atsushi-ishibashi any progress?

[atsushi-ishibashi]

PR was already sent...
Btw, this feature will be merged👍
https://github.com/terraform-providers/terraform-provider-aws/pull/1568

I'll close this issue in order not to confuse anyone.

[hashibot[bot]]

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