* Add new conf in admin page for supplier order classify billed without invoice
* Add translations en_US
* Add check on new config to allow or not the classify billed button
* Add possibility to set the hidden conf to disallow classify billed button from order, from the admin page
* Update conf names and move code to right parts, according to PR returns
# Qual: Fix PhanTypeExpectedObjectOrClassName by testing on classname
PhanTypeExpectedObjectOrClassName should be fixed by testing that the classname is not
empty.