fixes for opensuse

The changes to use cap-ng and not run as root have broken icecream on suse (and not only, I'd say) in a number of ways - log file can no longer be written to /var/log, env. cache directory can no longer be completely removed if in /var/cache/icecream, user is mixed to be 'icecream' or 'icecc', and chown() fails. I think I've fixed all of these and it seems to work fine now, but as this is security relatd stuff, I'd like a review before this goes in.