provider/aws: Rename the Import aws_opsworks_stack import test
provider/aws: Rename the Import aws_opsworks_stack import test

The casing on the test name was causing it not to run with the entire
test suite

```
% make testacc TEST=./builtin/providers/aws
% TESTARGS='-run=TestAccAWSOpsworksStack'             2 ↵ ✹
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /terraform/vendor/)
2016/10/03 16:43:07 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/aws -v -run=TestAccAWSOpsworksStack
-timeout 120m
=== RUN   TestAccAWSOpsworksStackImportBasic
--- PASS: TestAccAWSOpsworksStackImportBasic (49.00s)
=== RUN   TestAccAWSOpsworksStackNoVpc
--- PASS: TestAccAWSOpsworksStackNoVpc (36.10s)
=== RUN   TestAccAWSOpsworksStackVpc
--- PASS: TestAccAWSOpsworksStackVpc (73.27s)
PASS
ok      github.com/hashicorp/terraform/builtin/providers/aws158.385s
```

kjmkznr/terraform-provider-aws,terraform-providers/terraform-provider-aws,ClementCunin/terraform-provider-aws,charles-at-geospock/terraform-provider-aws,ClementCunin/terraform-provider-aws,nbaztec/terraform-provider-aws,terraform-providers/terraform-provider-aws,kjmkznr/terraform-provider-aws,terraform-providers/terraform-provider-aws,nbaztec/terraform-provider-aws,ashinohara/terraform-provider-aws,Ninir/terraform-provider-aws,kjmkznr/terraform-provider-aws,charles-at-geospock/terraform-provider-aws,ashinohara/terraform-provider-aws,charles-at-geospock/terraform-provider-aws,ClementCunin/terraform-provider-aws,Ninir/terraform-provider-aws,ashinohara/terraform-provider-aws,ClementCunin/terraform-provider-aws,nbaztec/terraform-provider-aws,kjmkznr/terraform-provider-aws,nbaztec/terraform-provider-aws,ashinohara/terraform-provider-aws,terraform-providers/terraform-provider-aws,charles-at-geospock/terraform-provider-aws,Ninir/terraform-provider-aws,Ninir/terraform-provider-aws