provider/aws: Add support for `network_mode` to `aws_ecs_task_definition` (#8391)
provider/aws: Add support for `network_mode` to `aws_ecs_task_definition` (#8391)

* provider/aws: Add support for `network_mode` to
`aws_ecs_task_definition`

Fixes #8281

```

```
make testacc TEST=./builtin/providers/aws TESTARGS='-run=TestAccAWSEcsTaskDefinition_'
==> Checking that code complies with gofmt requirements...
/Users/stacko/Code/go/bin/stringer
go generate $(go list ./... | grep -v /terraform/vendor/)
2016/08/22 18:12:20 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/aws -v -run=TestAccAWSEcsTaskDefinition_ -timeout 120m
=== RUN   TestAccAWSEcsTaskDefinition_basic
--- PASS: TestAccAWSEcsTaskDefinition_basic (29.02s)
=== RUN   TestAccAWSEcsTaskDefinition_withScratchVolume
--- PASS: TestAccAWSEcsTaskDefinition_withScratchVolume (16.75s)
=== RUN   TestAccAWSEcsTaskDefinition_withEcsService
--- PASS: TestAccAWSEcsTaskDefinition_withEcsService (147.77s)
=== RUN   TestAccAWSEcsTaskDefinition_withTaskRoleArn
--- PASS: TestAccAWSEcsTaskDefinition_withTaskRoleArn (19.49s)
=== RUN   TestAccAWSEcsTaskDefinition_withNetworkMode
--- PASS: TestAccAWSEcsTaskDefinition_withNetworkMode (19.52s)
PASS
ok  	github.com/hashicorp/terraform/builtin/providers/aws	232.588

* Update resource_aws_ecs_task_definition.go

* Update ecs_task_definition.html.markdown

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