Support for teams #117

Teams will be composed of a group of IAM users.

1. create the IAM group if it doesnt exist and add it in the global_config and in the local_config
2. at the end of every new stack deployment add the pollicy of the stack to the IAM group.
3. each stack should always contain an IAM policy and an IAM role in its template.
4. when the createIamUser method is used, a user is created and assigned to the group.