UI fixes to All apps pull up work

b/28917826
- nav bar change to light when top of the all apps container
passes y mid point of the status bar
- apps search edit box change when top of the all apps passes
the bottom of nav bar
- Restrict pull up to work only if the ACTION_DOWN event started
from the hotseat.
- Landscape: reverted old padding and margin. Only the interaction
is different.
- Tuning of the motion spec
- Animation duration respects fling speed more agressively.
- and many more small bugs...

Change-Id: Icde4093c41eeab8c9c6d9dc8b7d57adc3b171349