initial config for doctrine_mongodb

Basics for DocumentBundle that pulls in DoctrineMongoDBBundle.
odd based App document

This shall replace the Entity\App in CoreBundle but I'm not mucking with
that until this is up and running.
create AppRepository
make all CoreBundle documents loggable
basic get all apps implementation

injection and everything for getting closer to returning some values from mongodb.
install mongodb on travis
implement allAction

Quick implementation of the allAction method for demo purposes.
phpcs
more phpcs
even more phpcs
Merge branch 'feature/document-bundle' into develop