Fixes#8679
The CallerReference attribute we passed to AWS in route53_health_checks
was `time.Now().Format(time.RFC3339Nano)`
When creating multiple resources with the Count meta-parameter, this was
causing issues as follows:
```
* aws_route53_health_check.healthstate.0: HealthCheckAlreadyExists: A different health check has already been created with the specified caller reference.
```
We have now exposed a new attribute called `reference_name` that can be set to pass multiple resources to the request
```
make testacc TEST=./builtin/providers/aws TESTARGS='-run=TestAccAWSRoute53HealthCheck_' 130 ↵ ✹
==> Cecking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /terraform/vendor/)
2016/10/31 10:41:07 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/aws -v -run=TestAccAWSRoute53HealthCheck_ -timeout 120m
=== RUN TestAccAWSRoute53HealthCheck_importBasic
--- PASS: TestAccAWSRoute53HealthCheck_importBasic (17.08s)
=== RUN TestAccAWSRoute53HealthCheck_basic
--- PASS: TestAccAWSRoute53HealthCheck_basic (28.17s)
=== RUN TestAccAWSRoute53HealthCheck_withSearchString
--- PASS: TestAccAWSRoute53HealthCheck_withSearchString (28.07s)
=== RUN TestAccAWSRoute53HealthCheck_withChildHealthChecks
--- PASS: TestAccAWSRoute53HealthCheck_withChildHealthChecks (20.71s)
=== RUN TestAccAWSRoute53HealthCheck_IpConfig
--- PASS: TestAccAWSRoute53HealthCheck_IpConfig (16.09s)
=== RUN TestAccAWSRoute53HealthCheck_CloudWatchAlarmCheck
--- PASS: TestAccAWSRoute53HealthCheck_CloudWatchAlarmCheck (22.42s)
PASS
ok github.com/hashicorp/terraform/builtin/providers/aws 132.568s
```
Paul Stack