Support authenticationDatabase

MongoDB allows to have users to be defined in the 'admin' database that have permissions in other databases. See last example in http://docs.mongodb.org/manual/tutorial/add-user-to-database/. Before MongoDB 2.4, a login was automatically checked both in the database you connected to and in the 'admin' database. Since MongoDB 2.4, you need to explicitly mention the authentication database when logging in via the tools. If you login via the Java driver, you need to authenticate to the authentication database before you can connect to the target database.

This issue was recently fixed in Spring-Data-MongoDB 1.4.1, too: https://jira.spring.io/browse/DATAMONGO-789.