Add X in top left corner on all screens

[ehamner]

When kids are in a screen without the X in the corner and they want to leave the screen, they don't know how. The teachers have been using the swipe up and kindle navigation to get out of the screen. The student image icon in the top right corner will bring you back to the start/choose a student page, but no one realizes this. I still like being able to see the face of the student there, and it's ok that you can use it to go back, but having the X in the top left would be more consistent. Kids and teachers seem to look for that and get confused when it's not there.
(Observed Pilot 2, Week 2)