Check that invalid header error emails are suppressed

[alexlittle]

As we have on oppiamobile server

[alexlittle]

Suppressed the emails using null logging handler:

LOGGING = {
'version': 1,
'disable_existing_loggers': False,
'filters': {
'require_debug_false': {
'()': 'django.utils.log.RequireDebugFalse'
}
},
'handlers': {
'mail_admins': {
'level': 'ERROR',
'filters': ['require_debug_false'],
'class': 'django.utils.log.AdminEmailHandler'
},
'null': {
'level': 'DEBUG',
'class': 'logging.NullHandler',
},
},
'loggers': {
'django.request': {
'handlers': ['mail_admins'],
'level': 'ERROR',
'propagate': True,
},
'django.security.DisallowedHost': {
'handlers': ['null'],
'propagate': False,
},
}
}