PackageManager: Prevent themes from going into ASEC containers

Themes on ASEC cause all kinds of random timing/racey issues at boot
time, and more kinds of racey concurrency issues at uninstall/upgrade
time. Stop them from getting into containers at all.

Change-Id: If08e90c51137b22239831a4eca17ea00d5d87d93
Merge branch 'cm-10.2' into martincz