provider/aws: Add Support for Tags to aws_cloudwatch_log_group
provider/aws: Add Support for Tags to aws_cloudwatch_log_group

``````
make testacc TEST=./builtin/providers/aws TESTARGS='-run=TestAccAWSCloudWatchLogGroup_'                               2 ↵ ✭
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /terraform/vendor/)
2017/01/12 16:22:07 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/aws -v -run=TestAccAWSCloudWatchLogGroup_ -timeout 120m
=== RUN   TestAccAWSCloudWatchLogGroup_importBasic
--- PASS: TestAccAWSCloudWatchLogGroup_importBasic (44.20s)
=== RUN   TestAccAWSCloudWatchLogGroup_basic
--- PASS: TestAccAWSCloudWatchLogGroup_basic (38.08s)
=== RUN   TestAccAWSCloudWatchLogGroup_retentionPolicy
--- PASS: TestAccAWSCloudWatchLogGroup_retentionPolicy (55.85s)
=== RUN   TestAccAWSCloudWatchLogGroup_multiple
--- PASS: TestAccAWSCloudWatchLogGroup_multiple (20.68s)
=== RUN   TestAccAWSCloudWatchLogGroup_disappears
--- PASS: TestAccAWSCloudWatchLogGroup_disappears (21.48s)
=== RUN   TestAccAWSCloudWatchLogGroup_tagging
--- PASS: TestAccAWSCloudWatchLogGroup_tagging (39.09s)
ok
PASS	github.com/hashicorp/terraform/builtin/providers/aws	219.411s
```

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