Import error when requests module is not installed

[Jens Schmer]

Traceback (most recent call last):
  File "C:/Projects/Py/pmatic/debug_iterate_devices.py", line 31, in <module>
    import pmatic
  File "C:\Projects\Py\pmatic\pmatic\__init__.py", line 48, in <module>
    from pmatic.ccu import utils
  File "C:\Projects\Py\pmatic\pmatic\ccu.py", line 47, in <module>
    from pmatic.residents import Residents
  File "C:\Projects\Py\pmatic\pmatic\residents.py", line 29, in <module>
    import requests.exceptions
ImportError: No module named requests.exceptions