Restores tracking notifications detail view.

Confirmed event is showing up in mixpanel develop. Fixes #1995.
Merge branch 'release/3.4' into develop
update to undobar 1.6
Merge branch 'release/3.4' into develop
Merge branch 'develop' into feature/material-appcompat
ripple animation background for nux buttons
center about layout
Merge branch 'feature/material-appcompat' of github.com:wordpress-mobile/WordPress-Android into feature/material-appcompat