Pyilluminate

* Refactored how devices are identified. They are not identified by their
serial numbers instead of their MAC Address. This avoids port knocking and
ensures that openning devices is now faster especially when trying to
connect to multiple Illuminate devices connected to a single computer.

* Fixed up a typo that would cause an error to occur in `positions_as_xarray`.

* Improved the error message when trying to open an Serial connection that is already in use.

* Illuminate.led_positions is now an xarray instead of a numpy struct array.
* ``Illuminate.positions_as_xarray()`` is deprecated in favour of ``Illuminate.led_positions``.
* The attribute ``Illuminate.color`` can now be set with either a tuple or a simple scalar.

release-0.2.9

* Better access to the color/bightness property
* The array will turn itself off once you close python
* Clears LEDs when setting individual LEDs too.