Configuration object for Roller. Reads and writes roller-config.xml.
This file is a relic of the old days, back when we used to store the Roller
configuration in an XML file. In Roller 0.9.9 and later, this file only
exists to allow use to read only roller-config.xml files on startup and
copy them into the database.
Directory where uploaded files will be stored. May end with a slash.
Optional, this value will default to RollerContext.USER_RESOURCES. If
specified, should be a full path on the system harddrive or relative to
the WebApp.