core: bring original volume panel expand icon back

This one makes more sense from a UX standpoint
Update the color of the expandable volume panel icon

This still retains the old settings icon since it
happens to fit perfectly. Pressing it does indeed
show you a bunch of sliders like the icon indicates.

Also add xhdpi and xxhdpi versions.
Merge "core: bring original volume panel expand icon back" into kitkat
Merge "Update the color of the expandable volume panel icon" into kitkat
Merge remote-tracking branch 'PA/kitkat' into kitkat-remix