Processing errors in cache.xml do not log a warning

If there is an error in processing a cache.xml (like a class used in
cache.xml not present on the class path) we do not log any error or
warning in the logs.

An Exception is thrown back to the user and displayed in gfsh, but when scripting server starts, these errors may not be immediately visible.

It would be nice to log these errors in the server's log file.