split of dummification of categorical varibales into
- numerical mapping
- dummification on these numerical values
modified:   census/transformer.py
- Extract some constants out of load_datas
- fit Transformer in three stages instead of two due to changes of Transformer
	modified:   census/shortcuts.py
- comment corrected on sort_key was wrong
- sort_key bug corrected : must be float !

	modified:   census/learn.py
Added some kwoptions to load_datas
	modified:   census/shortcuts.py
- bug due to last commit change on shortcuts load_datas changes
see 5b5fb1f35688bf129c1e10f45c9b1eece66e075b
	modified:   census/transformer.py
minor changes
	modified:   run_lr.py
random forest learning
	new file:   run_rf_dumm.py
	new file:   run_rf_raw.py
	deleted:    run.py
Changes due to census lib code changes
	modified:   ipython/run.ipynb
updated
	modified:   README.md