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

[Ryan C. Gordon]

> 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.

(I thought I already fixed that, too, damn...)

I'll look at the other patches soon.

--ryan.