[java] move applicative code in app directory
Revert "[java] move applicative code in app directory"

This reverts commit f3cf8ffb0f5c18911675a8c79b8c9807ffae4640.
[java] Tests can pass on a platform with 'mvn -Dfr.valtech.host=exemple.org:80 clean install -f mepc-functionnal-tests/pom.xml'
Finish project moving
Merge branch 'master' into version-2

Conflicts:
	java/app/mepc-server/src/main/webapp/conf.js
[java] move back from java/app to java