Made DatabaseConfiguration compatible with the builder approach.

There are now set methods for the properties defining the database structures
the configuration operates on. The values of these properties can also be
queried which was requested by [CONFIGURATION-535].

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/configuration/trunk@1465759 13f79535-47bb-0310-9956-ffa450edef68
[CONFIGURATION-535] Updated changes.xml.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/configuration/trunk@1465761 13f79535-47bb-0310-9956-ffa450edef68