- Followup to PR #2773, where we started using official appengine Maven plugin than older ```maven-gae-plugin```
- ```appcfg``` script is deprecated and most of these works can be done through ```gcloud-appengine-sdk```
- More details in cl/333435946 (where we moved away from ```appcfg``` during the releases) and cl/xxxxx (We no more need any manual copy jar commands)