README: Update build dependency list

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>
Backend: remove predicted labels indexation:
It requires far too much time to update the predicted labels when starting.

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>
setup.py: update dependency list

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>
Merge branch 'unstable' into wip-label-prediction
Backend: Fix label prediction

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>