SystemUI: fix recents minimization animation

Splitting up the buttons into each class is cute,
but it only seemed to complicate its interactions.
The instantiation was wrong before anyways and
onTouchListener was never being registered
(which is why the animation was wonky).

Change-Id: I4194569aaf0099754852d5cfb83f308f3271008b
Signed-off-by: Roman Birg <romanbirg@gmail.com>
SystemUI: RAM bar view optimizations

findViewById() was being called every time updateSettings()
was being called. Instead, let's instantiate them once, and
remove calls to updateSettings() since it will be called
on its own when the setting values change.

Change-Id: Iaa02343caccb615921219be2a56b3bac4f3263b9
Signed-off-by: Roman Birg <romanbirg@gmail.com>