[IZPACK-1126]

A proposed improvement to the process panel as detailed on http://jira.codehaus.org/browse/IZPACK-1126.

The idea is to have process panel jobs structured in such a way as to emulate java's try/catch/finally statements, so catch jobs can run in response to failures, and final jobs can run regardless of the success or failure of other jobs.

<job> elements in the ProcessPanel.Spec.xml can have 'catch' and 'final' attributes. If these attributes are present and set to true, the process job is added to the 'catch' or 'final' process job group respectively. 

The jobs in the 'catch ' group are run only in the event of some process panel job failure.
The jobs in the 'final' group are run regardless of failure or success in previous jobs.