Fix iam instance profile

[chroju]

Fix issue #374 .

Because the "roles" argument in aws_iam_instance_profile is deprecated,
use "role" instead in tf and tfstate.
cf: AWS: aws_iam_instance_profile - Terraform by HashiCorp

In addition, remove the test case with 0 role. In this case, terraform will output the following error.

Error applying plan:

1 error(s) occurred:

* aws_iam_instance_profile.test_profile: 1 error(s) occurred:

* aws_iam_instance_profile.test_profile: Either `role` or `roles` (deprecated) must be specified when creating an IAM Instance Profile

[coveralls]

Coverage remained the same at 100.0% when pulling 45053e5 on chroju:fix_iam_instance_profile into f4e3040 on dtan4:master.

[dtan4]

(mistaken! this comment was moved to #370 (comment))

[dtan4]

This field change was introduced at hashicorp/terraform#13130 and released at Terraform v0.9.3.

[dtan4]

LGTM 👍 Thanks ❗️