This release of `aws-creds` introduces the ability to assume roles. To facilitiate this, the following features have been added under the `roles` subcommand:
1. add: Adds a role.
2. assume: Assumes a saved role.
3. ls: Lists all roles available to be assumed.
4. rm: Removes an assumed role permanently from aws-cred config.
5. unassume: Unassumes a role, switching back to source account.
*N.B.* `aws-creds` does not yet support roles that require mfa.