Remove duplication of AppEngine stuff

[ggalmazor]

There is some duplicated AppEngine related stuff in src/main/gae_ear and installer/gae.zip

The installer related Gradle scripts could probably use src/main/gae_ear instead of unzipping installer/gae.zip

Software and hardware versions

Any

Problem description

Duplicated stuff makes changes harder to do

Steps to reproduce the problem

This is an issue with just the code

Expected behavior

N/A

Other information

N/A