Remove atfork (it's not needed anymore)

manage.py

@@ -2,13 +2,7 @@
 """
 CLI to manage redash.
 """
-import atfork
 import signal
-
-atfork.monkeypatch_os_fork_functions()
-import atfork.stdlib_fixer
-atfork.stdlib_fixer.fix_logging_module()
-
 import logging
 import time
 from redash import settings, app, db, models, data_manager, __version__

requirements.txt

@@ -8,7 +8,6 @@ MarkupSafe==0.18
 WTForms==1.0.5
 Werkzeug==0.9.4
 aniso8601==0.82
-atfork==0.1.2
 blinker==1.3
 flask-peewee==0.6.5
 itsdangerous==0.23