Added backgroundFile field.
Added images list by step.
New changements on the game plan: the background is now a little movie, with a cinematic for the introduction and a loop for the steps.
Merge branch 'generatorViewChangements' into generatorView

Conflicts:
	src/fr/intechinfo/doctorj/controllers/GeneratorStep.java
	src/fr/intechinfo/doctorj/model/Step.java
	src/fr/intechinfo/doctorj/views/generatorStep.fxml
Failed merge on GeneratorStep ^-^ Pushed corrections.
Merge remote-tracking branch 'origin/develop' into generatorView