2.7 stub updates (#149)

* Stubgen modules for 2.7

Cookie
email._parseaddr
email.utils
genericpath
linecache
mimetypes
multiprocessing
multiprocessing.process
multiprocessing.util
posixpath
quopri
runpy
weakref
wsgiref.validate

* 2.7/typing.py: add missing __contains__ definition

* 2.7/subprocess.py: make output argument to CalledProcessError optional

Commit f08160bd did the same for py3.

* 2.7/hmac.pyi: add compare_digest

This function was introduced to the 2.7 series in 2.7.7.

* Stubgen 2.7/ssl.pyi

This replaces a nearly-empty handwritten stub.

* Copy constants and other definitions from py3 to py2 ssl.pyi

* 2.7/__future__.pyi: add methods

* 2.7/_weakref.pyi: backport some definitions from 3.x version

* Stubgen 2.7/locale.pyi

Hand-edited to remove declarations that are redundant (and cause
conflicts with) the "from _locale import *" line.

stdlib/2.7/linecache.pyi

@@ -0,0 +1,7 @@
+# Stubs for linecache (Python 2)
+#
+# NOTE: This dynamically typed stub was automatically generated by stubgen.
+
+def getline(filename, lineno, module_globals=None): ...
+def clearcache(): ...
+def checkcache(filename=None): ...