Readme additional hint for debug print

[NicoHood]

I am using the following to easily debug my bridge messages. It could be worth to add this to the readme:

# Print bridge debug content
def bprint(*args, **kwargs):
    print(yaml.safe_dump(*args, **kwargs, indent=4))

Fits into this section: https://github.com/quentinsf/qhue#a-couple-of-hints