Accept domains without extension in set_app_domain

set_app_domain.py

@@ -24,7 +24,7 @@ class SetAppDomain():
          by using this format: ms-<instance name> (for example ms-msuser).
     domain: The new domain.''' % __file__
     UNIX_USER_PATTERN = r'[a-z0-9\-]+'
-    DOMAIN_PATTERN = r'([a-z0-9\-]+\.)*[a-z0-9\-]+\.[a-z]+'
+    DOMAIN_PATTERN = r'([a-z0-9\-]+\.)*[a-z0-9\-]+(\.[a-z]+){0,1}'
 
     def __init__(self, *args):
         args = list(args)