Merge pull request #1 from MalkIPP/master

Remove annoying print
Remove unused Scenario._isPopulated.
Add "main-d-oeuvre" option to Bareme.
Fix conflict
Fix nmen=1 problem
Rework & rename calculate methods.
Improve Column & Prestation attributes.
Code cleanup.
Enhance Bareme.multTaux
Fail when column doesn't exist.
Remove useless variable.
Merge branch 'master' of https://github.com/openfisca/openfisca-core

Conflicts:
	openfisca_core/datatables.py