CM11 Themes: Fix how common resources are found

During the boot process, application info may not be fully
available and createPackageContext can throw a null pointer which
causes a theme's resource-cache to be cleared.  If this theme is
in /system/app or /system/priv-app the theme will still be installed
but applying it will result in styles not being applied.

Change-Id: I4094bdd923edc1d829024404a4ce1b72709bd4f1
Themes: Support launcher based icon packs [1/2]

Before this patch, icon packs written for Trebuchet/Nova/Apex could not be used
with the new theme engine as the formats were different. Particularly the icon package IDs are 7F,
the same ID as as regular apps. Furthermore the location of resources in these icon packs was different
from what the theme engine expects. This patch adds support for these icon packs by overriding
the pkg id.

AssetManager now can override package ids without requiring aapt to recompile the APK.
Note: XML references will still use the original id compiled with AAPT, so it is only useful for resources
which do not use xml drawables (such as icon packs).

PackageInfo now has a new member identify "legacy" (3rd party icon packs) written
for launcher's like Trebuchet, Nova, and Apex.

Change-Id: Icd12c097e156c9626df0772abeb50e00f7b61f64

Conflicts:
	core/java/android/app/IconPackHelper.java
	core/java/android/content/pm/PackageInfo.java
	core/java/android/content/pm/PackageParser.java
	core/java/android/content/res/Resources.java
	core/jni/android_util_AssetManager.cpp
	include/androidfw/AssetManager.h
	libs/androidfw/AssetManager.cpp
	libs/androidfw/ResourceTypes.cpp