Adapter refactor

Allows using different ways to retrieve hosts IP address

transip_client/utils.py

@@ -0,0 +1,10 @@
+from importlib import import_module
+from typing import Type
+
+from transip_client.adapters import Adapter
+
+
+def import_string(path: str) -> Type[Adapter]:
+    module_path, class_name = path.rsplit(".", 1)
+    module = import_module(module_path)
+    return getattr(module, class_name)