provider/aws: Add validation to IAM User and Group Name

[stack72]

This will allow us to catch errors at plan time rather than waiting for
the API to tell us...

Documentation for IAM User NAme Validation -
http://docs.aws.amazon.com/cli/latest/reference/iam/create-user.html

Documentation for IAM Group Name validation -
http://docs.aws.amazon.com/cli/latest/reference/iam/create-group.html

% make testacc TEST=./builtin/providers/aws TESTARGS='-run=TestAccAWSIAMGroup_'
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /terraform/vendor/)
2016/10/25 13:18:41 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/aws -v -run=TestAccAWSIAMGroup_
-timeout 120m
=== RUN   TestAccAWSIAMGroup_importBasic
--- PASS: TestAccAWSIAMGroup_importBasic (13.80s)
=== RUN   TestAccAWSIAMGroup_basic
--- PASS: TestAccAWSIAMGroup_basic (23.30s)
PASS
ok      github.com/hashicorp/terraform/builtin/providers/aws37.121s

% make testacc TEST=./builtin/providers/aws TESTARGS='-run=TestAccAWSUser_'                                                                 ✚
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /terraform/vendor/)
2016/10/25 13:22:23 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/aws -v -run=TestAccAWSUser_ -timeout 120m
=== RUN   TestAccAWSUser_importBasic
--- PASS: TestAccAWSUser_importBasic (14.33s)
=== RUN   TestAccAWSUser_basic
--- PASS: TestAccAWSUser_basic (25.36s)
PASS
ok      github.com/hashicorp/terraform/builtin/providers/aws    39.710s

[bandesz]

I opened an issue about this to allow underscores, because it seems the AWS documentation is not correct. #9679

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

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