FIx AA_MODEL meta-data bug

The mechanism for AA_MODEL was error-prone in that it assumed the
application package name would always match the src code package
name. This made it easier to define AA_MODEL classes by using
shortcut notation. Unfortunately, this is problematic when the
application package name differs from the src code package name,
which comes up most often with Gradle build variants where the
application package name changes on a build by build basis.