Make distance count when dismissing swipedismisslayout

verify the user's gesture took up at least 40% of the screen
before dismissing
Part of b/14319825 Cliff guard against accidental card dismissals

Works in conjunction with GridViewPager change:
https://googleplex-android-review.git.corp.google.com/#/c/461036/
Change-Id: Id8ff02d0a2d727b54c9950ad14ddef7a110f4eef