move cgi to 2and3 and add types (#1022)

* move cgi to 2and3 and add types

This is pretty stable between Python 2 and 3, and not very well documented.

* fix CI failures

* adjust comment

(want to force Travis to re-run)

* give up on overriding values

stdlib/3/cgi.pyi

@@ -1,4 +0,0 @@
-from typing import Dict, Tuple
-
-def escape(s: str, quote: bool = ...) -> str: ...
-def parse_header(s: str) -> Tuple[str, Dict[str, str]]: ...