provider/aws: Adding a datasource for aws_ebs_volume (#9753)
provider/aws: Adding a datasource for aws_ebs_volume (#9753)

This will allows us to filter a specific ebs_volume for attachment to an
aws_instance

```
make testacc TEST=./builtin/providers/aws TESTARGS='-run=TestAccAWSEbsVolumeDataSource_'✹
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /terraform/vendor/)
2016/11/01 12:39:19 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/aws -v
-run=TestAccAWSEbsVolumeDataSource_ -timeout 120m
=== RUN   TestAccAWSEbsVolumeDataSource_basic
--- PASS: TestAccAWSEbsVolumeDataSource_basic (28.74s)
=== RUN   TestAccAWSEbsVolumeDataSource_multipleFilters
--- PASS: TestAccAWSEbsVolumeDataSource_multipleFilters (28.37s)
PASS
ok      github.com/hashicorp/terraform/builtin/providers/aws57.145s
```
Ninir/terraform-provider-aws,ashinohara/terraform-provider-aws,nbaztec/terraform-provider-aws,Ninir/terraform-provider-aws,charles-at-geospock/terraform-provider-aws,ashinohara/terraform-provider-aws,charles-at-geospock/terraform-provider-aws,ClementCunin/terraform-provider-aws,terraform-providers/terraform-provider-aws,nbaztec/terraform-provider-aws,Ninir/terraform-provider-aws,nbaztec/terraform-provider-aws,ClementCunin/terraform-provider-aws,kjmkznr/terraform-provider-aws,charles-at-geospock/terraform-provider-aws,kjmkznr/terraform-provider-aws,charles-at-geospock/terraform-provider-aws,ClementCunin/terraform-provider-aws,ashinohara/terraform-provider-aws,kjmkznr/terraform-provider-aws,terraform-providers/terraform-provider-aws,nbaztec/terraform-provider-aws,terraform-providers/terraform-provider-aws,ClementCunin/terraform-provider-aws,kjmkznr/terraform-provider-aws,terraform-providers/terraform-provider-aws,Ninir/terraform-provider-aws,ashinohara/terraform-provider-aws