* Rename ids to something meaningful
* Remove inner layouts from constraint layout
* Use same text and button styles
* Make sure the background image doesn't overlap with the text
This uses the new Storage Access Framework, which was required for
accessing files on the SD Card starting in android-19. But the API
was really limited until android-21, and not really complete until
android-23 or even android-26. So the levels of usability will vary a
lot based on how new the version of Android is.
