updated composer.json for Symfony 2.3
updated composer.json for Symfony 2.3

sarcher/DoctrineMongoDBBundle,castarco/DoctrineMongoDBBundle,stof/DoctrineMongoDBBundle,malarzm/DoctrineMongoDBBundle,doctrine/DoctrineMongoDBBundle,jahller/DoctrineMongoDBBundle,malarzm/DoctrineMongoDBBundle,0mars/DoctrineMongoDBBundle,Soullivaneuh/DoctrineMongoDBBundle,tomasbro/DoctrineMongoDBBundle,juchi/DoctrineMongoDBBundle,alcaeus/DoctrineMongoDBBundle,jahller/DoctrineMongoDBBundle,juchi/DoctrineMongoDBBundle,castarco/DoctrineMongoDBBundle,alcaeus/DoctrineMongoDBBundle,Soullivaneuh/DoctrineMongoDBBundle,tomasbro/DoctrineMongoDBBundle,0mars/DoctrineMongoDBBundle