FB: Heads Up background color && transparency [2/2]

    PS: manual rebase

    PS: fix my retardedness

    PS: fix heads up TRDS background resources

    PS: clear content holder background prior to setting TRDS
            drawable so that correct drawable for TRDS state
            is set

    PS: revert non-TRDS background to AOSP gray (default
            system notification background color)

    PS: clean up some unused code

    PS: add capability to set custom heads up text color
    Change-Id: I3942c0ce178491e3429e5ae7eb24b43ba07a1f40

    Conflicts:
        core/java/android/provider/Settings.java
        packages/SystemUI/src/com/android/systemui/statusbar/BaseStatusBar.java

Change-Id: I1f7c115cf72e647e3639b77c24ceb05aa75cb9a8