Separate 3rd party imports from stdlib imports and local imports.
http://www.python.org/dev/peps/pep-0008/#imports

```python
import logging
import os

from Queue import Queue, Empty

from twisted.internet import threads, defer
from twisted.internet.task import LoopingCall
from twisted.python import log

import zope.interface

from leap.bitmask.config.providerconfig import ProviderConfig
from leap.bitmask.provider.providerbootstrapper import ProviderBootstrapper
```