modules/s3-remote-state: Add conditional region variable

Added a `variable` to the main.tf file and updated the README accordingly

Fixes: #100

TODO: test this one the dev-sandbox

modules/s3-remote-state/README.md

@@ -50,6 +50,7 @@ Create a `terraform.tfvars`, for example:
 ```hcl
 principals="<arn of principal>"
 bucket_name="fpco-tf-remote-state-test"
+region="us-east-1"
 ```
 
 Now it's time to create  the `IAM` policies and `S3` bucket using Terraform.
@@ -175,4 +176,4 @@ If for any reason you no longer need this state and bucket, you can delete it as
 2. Manually delete the contents of the `S3` bucket
 3. Run `terraform destroy`
 
-[1]: https://www.terraform.io/docs/backends/config.html
+[1]: https://www.terraform.io/docs/backends/config.html

modules/s3-remote-state/main.tf

@@ -4,8 +4,9 @@
  * This module creates a private S3 bucket and IAM policy to access that bucket.
  * The bucket can be used as a remote storage bucket for `terraform`, `kops`, or
  * similar tools.
- * 
+ *
  */
+
 variable "bucket_name" {
   description = "the name to give the bucket"
 }
@@ -20,14 +21,23 @@ variable "versioning" {
   description = "enables versioning for objects in the S3 bucket"
 }
 
+variable "region" {
+  default     = ""
+  description = "Region where the S3 bucket will be created"
+  type        = "string"
+}
+
 variable "aws_cloud" {
   description = "set to 'aws-us-gov' if using GovCloud, otherwise leave the default"
   default     = "aws"
 }
 
+data "aws_region" "current" {}
+
 resource "aws_s3_bucket" "remote-state" {
   bucket = "${var.bucket_name}"
   acl    = "private"
+  region = "${var.region == "" ? data.aws_region.current.name : var.region}"
 
   versioning {
     enabled = "${var.versioning}"