Restructure folder, create gitpull release

Summary:
Move java source to app/src/main/java

Move AndroidManifest to app/src/main folder

Same for debug version

Create new variant "gitpull" for the phabricator build

Test Plan: Check it work by performing "./gradlew assembleGitpull"

Reviewers: valerio.bozzolan

Reviewed By: valerio.bozzolan

Subscribers: valerio.bozzolan, Libre BusTO

Tags: Libre BusTO

Differential Revision: https://gitpull.it/D117