Continue work on MongoDB support for Slick

by Adam Kożuch for Scala Team

My proposal is to update and improve previous implementation of MongoDB driver and make missing piece, hence support for nested documents, arrays and DBRefs which are essential in mongo databases and in practice most of mongo documents use it. To do that it is necessary to make some changes in Slick internals. My idea is to provide more flexible type system in slick and make mongo driver use it.