python 3 compatability changes

[guacamolepig]

Python 3 throws up issues when installing and running. I think these changes fix it but they probably need tested to make sure no new bugs are created.

.\commanduino_init_.py:
line 18 (change): 'from .commandmanager import CommandManager'

.\commanduino\commanddevices\commandsht1x.py:
line1 (change): 'from .commanddevice import CommandDevice'

.\commanduino\command_handler.py:
line 68 (addition): 'a_char = a_char.decode("utf-8")'

[Tyrannican]

Working on it!

[Tyrannican]

Fixed the issue, works on python2 and python3

[jgrizou]

👍