[mojosetup] Allow an uninstall to proceed if one file does not delete

[Jeremy White]

Ryan C. Gordon wrote:
> 
>> If, for example, we can't delete a directory, the uninstallation aborts.
>> But this option allows it to continue and clean up as much as it can.
> 
> The right approach is probably to realize the directory is gone, which
> is what we wanted anyhow, and call it success.
> 

Actually, I think the problem is that our postinstall process put a few
extra files into one of the installation directories, and so the
directory can't be removed (because there are still files in it).

Cheers,

Jeremy