Allow environment variable substitution in sql config

[maxbes]

Currently, it's not possible to use environment variables in sql-map-config.xml or in files mentionned in sql-map-config.xml (such as the file containing actual SQL queries)

I would like to be able to do something like this:

        <select id="getUserList" resultClass="java.util.HashMap">
                SELECT pivot
                FROM users
                WHERE login = "${USER_LOGIN}"
        </select>