Support CloudFormation service roles for all stack actions

[bengel-ias]

We are using a service role for managing permissions by the cloudformation plugin. See https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-iam-servicerole.html for details. This means that we need to pass the roleArn into the cloud formation clients requests. See the Javadoc for relevant property: https://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/services/cloudformation/model/CreateStackRequest.html#setRoleARN-java.lang.String-

This could be as simple as a new property 'cloudformation.roleArn' in AbstractCloudformationMojo that is used in all create/update/delete stack requests.

[aldrinleal]

PRs are welcome!