core: add support for translucent volume panel

Add support for display the volume panel in translucent mode

Patchset 4: Make it depends to high-end graphics flag

Change-Id: I4f21a6cc88282789072a0e71ae696b754a5e083e
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>
core: fix volume panel more button transparency

Change-Id: I9f728256efbaf138611822079ea7737cd345bb19
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>
Decrease Vol Panel Transparency

As I was kindly told at dinner...160 is aparently too transparent. Bump to 208,
 50% of difference of previous value and 255.

Change-Id: I938d0e37b5807c83d25a35e2fb08fcdfb02db18f