Improved the transitions and layout of the app name in conversations

The transition was using getTop instead of absolute positions which
didn't work well for the conversation layout.
Also, we were fading in views that were GONE and making them VISIBLE
which lead to bugs during the transitions.
Additionally, the header text would become visible when a notification
was removed from a group and reset.

Bug: 150905003
Test: visual, add conversations in groups and non-groups
Change-Id: I3c31006a1fc79f7d58cc1dd3d5af44129c9f02bb