Added django prefix to log files.

Added prefix since other log files might be written to the same
directory.
Fixed issue when visiting home page on production server.

When running on a production server visiting the home page would
trigger a 500 error, instead of redirecting to the appropriate
languahe, unless DEBUG was True. The problem appeared to occur
even when a trailing slash was added. Eventually tracked down
to the APPEND_SLASH setting used in the LocaleMiddleware. Once
set to True everthing works as expected.
Added default language setting for transmeta