Normalize game architecture

android/app/build.gradle

android/gradle.properties

assets/files/images.json

assets/fonts/Nunito-Bold.ttf

assets/fonts/Nunito-Light.ttf

assets/fonts/Nunito-Medium.ttf

assets/fonts/Nunito-Regular.ttf

assets/icons/difficulty_3x3.png

assets/icons/difficulty_4x4.png

assets/icons/difficulty_5x5.png

assets/images/placeholder.png

assets/translations/en.json

assets/translations/fr.json

assets/ui/button_back.png

assets/ui/button_delete_saved_game.png

assets/ui/button_random_pick.png

assets/ui/button_resume_game.png

assets/ui/button_shuffle.png

assets/ui/button_start.png

assets/ui/game_win.png