Miscellaneous contact-detail fixes.

Fix bug in carousel "Updates" tab, which would turn black when swiping
it all the way to the left.  This was caused by a small negative alpha
being computed, and some incautious integer arithmetic to transform it
for use in setBackgroundColor().  Fix clamps the alpha value between 0
and 1 (using newly-introduced MoreMath class).

Fix visual glitch where the "Updates" label displays the "pushed" glow
when tapped.

Bug: 6009463
Change-Id: Iee041ee7793f198f1d51ea5e7c5bbcb07b9a41df