Installing twilio on Python 3.4 doesn't install socks

When installing twilio, the requirement for socks isn't installed by pip. See also the following console actions on a freshly created virtual environment.

```
$ python -V
Python 3.4.2

$ pip -V
pip 1.5.6 from lib/python3.4/site-packages (python 3.4)

$ pip install twilio
Downloading/unpacking twilio
  Downloading twilio-3.6.13-py2.py3-none-any.whl (166kB): 166kB downloaded
Downloading/unpacking httplib2>=0.7 (from twilio)
  Downloading httplib2-0.9.tar.gz (204kB): 204kB downloaded
  Running setup.py (path:build/httplib2/setup.py) egg_info for package httplib2

Requirement already satisfied (use --upgrade to upgrade): six in lib/python3.4/site-packages (from twilio)
Installing collected packages: twilio, httplib2
  Running setup.py install for httplib2

Successfully installed twilio httplib2
Cleaning up...

$ python -c "import twilio"
Traceback (most recent call last):
  File "lib/python3.4/site-packages/twilio/rest/resources/imports.py", line 22, in <module>
    from httplib2.socks import (
ImportError: No module named 'httplib2.socks'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "lib/python3.4/site-packages/twilio/__init__.py", line 11, in <module>
    from .rest.exceptions import TwilioRestException
  File "lib/python3.4/site-packages/twilio/rest/__init__.py", line 6, in <module>
    from .resources import (
  File "lib/python3.4/site-packages/twilio/rest/resources/__init__.py", line 4, in <module>
    from .imports import (
  File "lib/python3.4/site-packages/twilio/rest/resources/imports.py", line 28, in <module>
    import socks
ImportError: No module named 'socks'
```

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