Update Launcher to use theme colors.

Instead of using hard-coded variants of colors, use the theme color
that corresponds (colorAccent, colorPrimary, etc).

Updated:
- "Search for more apps" text
- App info drop target hover color
- PageIndicatorDots
- All apps & widget scroll bar & scroll popup colors
- All apps section text color
- widget picker background color

TODO:
- widget picker header color

BUG: 28625102
Change-Id: I74b543ff71b8caef8cd950c8183ac84c759cb4d5

src/com/android/launcher3/allapps/AllAppsContainerView.java

@@ -178,7 +178,7 @@ public class AllAppsContainerView extends BaseContainerView implements DragSourc
         super(context, attrs, defStyleAttr);
         Resources res = context.getResources();
 
-        mLauncher = (Launcher) context;
+        mLauncher = Launcher.getLauncher(context);
         mSectionNamesMargin = res.getDimensionPixelSize(R.dimen.all_apps_grid_view_start_margin);
         mApps = new AlphabeticalAppsList(context);
         mAdapter = new AllAppsGridAdapter(mLauncher, mApps, this, mLauncher, this);