Loading a ContentState can lead to images partially offscreen or not centered

[abrin]

We’re using the ContentState API to allow for clean transitions to full-screen and back. But, I believe because the viewport is a significantly different ratio that this is not working properly.
a. The user experience is also quite awkward with the image bouncing (perhaps we can set the transition to immediate), or expose that as an option?
b. it feels like the image is also not positioned with the center of the target area in the center of the viewport (this feels like an atlas bug)

see #256 for illustration