Add missing List imports.

stdlib/3/email/charset.pyi

@@ -1,6 +1,6 @@
 # Stubs for email.charset (Python 3.4)
 
-from typing import Optional, Iterator, Any
+from typing import List, Optional, Iterator, Any
 
 class Charset:
     input_charset = ...  # type: str

stdlib/3/email/message.pyi

@@ -1,7 +1,7 @@
 # Stubs for email.message (Python 3.4)
 
 from typing import (
-    Optional, Union, Tuple, TypeVar, Generator, Sequence, Iterator, Any
+    List, Optional, Union, Tuple, TypeVar, Generator, Sequence, Iterator, Any
 )
 import sys
 from email.charset import Charset

stdlib/3/email/policy.pyi

@@ -1,7 +1,7 @@
 # Stubs for email.policy (Python 3.4)
 
 from abc import abstractmethod
-from typing import Any, Optional, Tuple, Union, Callable
+from typing import Any, List, Optional, Tuple, Union, Callable
 import sys
 from email.message import Message
 from email.errors import MessageDefect