updated auth token handling using new users api.

mdrsclient/api/__init__.py

@@ -1,11 +1,11 @@
 from mdrsclient.api.file import FileApi
 from mdrsclient.api.folder import FolderApi
 from mdrsclient.api.laboratory import LaboratoryApi
-from mdrsclient.api.user import UserApi
+from mdrsclient.api.users import UsersApi
 
 __all__ = [
     "FileApi",
     "FolderApi",
     "LaboratoryApi",
-    "UserApi",
+    "UsersApi",
 ]