Make switch access work for incoming call screen

An accessibility click on the glowpad now exposes the touch targets
as virtual views to accessibility services. Performing an accessibility
click on each virtual view performs the same function as swiping towards
that target.

Mark contact photo as unimportant for accessibility, it doesn't provide
any useful context or functionality.

Bug: 19075527
Change-Id: I2e980394175bf77379f5cb99126dd5970e0f0555