Outsource LED-Matrix Logic from station.py and introduce unit test

[Spansky]

The LED-Matrix follows a certain logic:

0 0 0
0 0 0
0 0 0

...is an LED-matrix that is completely dark.

9 9 9  
9 9 9  
9 9 9  

...is an LED-matrix that is completely lit.

Currently the code triggers the sensor directly, making it impossible to run a unit test.

By introducing the matrix-logic from above we increase code quality as it can be tested and reused.