Allow defining more than one model package in conf

exemple : module A use  modulea.models package name to store its OrientDB models, and module B use moduleb.models . Module C require module A and module B and contain the database settings in its application.conf.
With this change we can list package name (comma separated values in application.conf)

Signed-off-by: Rémi Parain <rparain@ubidreams.com>