IconPackHelper: Respect the original size of bitmap icons

When use icon packs on low-resolution devices, for example, my HDPI
phone, it seems that using the size returned by
getLauncherLargeIconSize() will cause a blurness on
some icons that are not included in the icon pack because of the compose
function.

This patch respects the original size of the icon if the icon is an
instance of BitmapDrawable but use the size returned by
getLauncherLargeIconSize() if the icon is an instance of PaintDrawable.
This will remove icon blurness on low-resolution devices.

Change-Id: Ifcb39020d934a9c7cb409e1206a179d64f99aa37
Restore lazy loading of LoadedApk resources

This was broken in 8fff544ec349593cfa61ae2f5ec59419fff666b6. Since that change,
resources are always initialized in getPackageInfo(), even if they haven't been
loaded before (mResources == null).

It shouldn't be necessary in *any* case to preload the resources at this point.
Anything using the resources should call LoadedApk.getResources(), which will
initialize them just when needed. Setting mResources to null resets the cache
and will force a reload the next time the resources are requested.

Change-Id: I9bc9986297478e99752b1e2b9bd04dab3dcc9656
Merge remote branch 'aokp/kitkat' into kitkat