Drop use of bitstring library and use manual bit ops

It seems that using bitstring to decode bit arrays is nearly 5-6 times
slower than manual bit operations.
Improve libusb handling
Use libusb by default
Pass cipher object instead of the key for simplicity
Change hidraw to direct to prevent confusions with hidapi stuff
Parse qualities, implement datalogger inside __main__

utils/datalogger is now implemented as __main__ in epoc.py. Fixes #1