Added variables support, setup.py and fixed deep update crash

Hi Axel,

It's great that you've created this package! I've updated it a bit:

* added `setup.py` so it can be installed via `pip`
* added accessing variable value
* fixed bug which happened when one of your devices was due to deep update

Also there's small refactoring. Instead importing `from spark_cloud import SparkCloud` now it's `from Spyrk import SparkCloud`. I did this to avoid three different names to remember (spyrk, spark_cloud and SparkCloud).