Expanding controller.py with basic user functions, get_models and destroy (#89)

Expanding controller.py with basic user functions, get_models and destroy (#89)

* Added user functions to controller.py, as well as the get_models call

* Fixes in controller.py

* Added controller.py integration tests

* Small fix in integration test

* Removed typo

* Disabled=False in controller.get_user does not work

* Added grant calls for model and controller, add-ssh, remove-ssh, get-ssh and get-machines

* Added last calls

* Added model.revoke('username')

* Edited docstring

* Added integrationtest for controller.py

* Fixed indentation error

* Added async

* Fixed type

* Fixed typo

* Expanded model integration tests

* Fixed typo

* ssh-key

* Typo

* Fix in remove_ssh_key

* Disconnecting models

* Added missing awaits

* Fixes

* Fixes

* Fixes

* Fixes

* Fixes

* Fixes

* Removed await in model grant

* Corrected remarks

* Typo

* Fixed tab error

* Typo

* Removed typo's

* Removed list from await expression

* Removed not needed await

* Added missing import

* Test

* Added decorators

* Merged #102

* Typo

* Updated _client.py

* Merged another