#3 update - case sensitivity

[Matt]

I found when running the update process (system update)
that the system was not detecting the version
installed. I manually updated the config file to have
the current version, but found that the script was
simply not detecting the variable.

Issue seems to be a case sensitivity problem. The
variable as declard in the config is lower case:
$config_version = "2.0.2-r6";
The xml-version.php script, however, references the
variable in caps:
$CONFIG_VERSION

I altered the script to use the lower case form of the
variable to resolve the problem.