trim blacklist (#370)

Remove files that now work with pytype from blacklist.

tests/pytype_blacklist.txt

@@ -1,16 +1,12 @@
 # Pytype blacklist. Files will not be tested with pytype.
 
 2.7/Cookie.pyi
-2.7/SocketServer.pyi
 2.7/StringIO.pyi
 2.7/__builtin__.pyi
-2.7/__future__.pyi
 2.7/argparse.pyi
 2.7/builtins.pyi
 2.7/calendar.pyi
 2.7/codecs.pyi
-2.7/collections.pyi
-2.7/csv.pyi
 2.7/email/utils.pyi
 2.7/functools.pyi
 2.7/inspect.pyi
@@ -23,10 +19,8 @@
 2.7/socket.pyi
 2.7/sqlite3/dbapi2.pyi
 2.7/ssl.pyi
-2.7/subprocess.pyi
 2.7/threading.pyi
 2.7/time.pyi
-2.7/token.pyi
 2.7/types.pyi
 2.7/typing.pyi
 2.7/unittest.pyi
@@ -45,18 +39,5 @@
 2and3/webbrowser.pyi
 
 # These cause problems for different reasons from above
-2.7/_functools.pyi
-2.7/array.pyi
-2.7/ast.pyi
-2.7/encodings/utf_8.pyi
-2.7/fcntl.pyi
-2.7/itertools.pyi
-2.7/json.pyi
-2.7/multiprocessing/process.pyi
-2.7/pickle.pyi
-2.7/tempfile.pyi
 2and3/argparse.pyi
-2and3/bz2.pyi
-
-# fail because of conditionals pytype#28
 2and3/zipfile.pyi