#24 --clean doesn't kill the .fcache

[Evan Jones]

If you run curator --clean, it doesn't delete the .fcache. Maybe it
should?

For example, I first ran curator without --pil, and then I couldn't
figure out why my images had a width and height of zero. So I ran
curator --clean to try and fix it. I finally blew away the directory
and restarted, and I figured out the .fcache thing.

Curator is awesome! Bravo!