FB: Slimrecents background color && transparency [1/2]

PS: now setting sticks through reboots and TRDS state
        changes. also, add reset to default color option.

PS: when resetting to default, use TRDS (png) resources
        instead of custom color

PS: remove LSN dependency

PS: make default background setting cognizant of
        recent panel gravity setting to display
        correct background resource
Change-Id: Icf0259ce45d416364d6e7a7a8c2038f6c4c0cbde