add funcionality on spacewalk-data-fsck to remove the RPM which does not match checksum

This patch adds the ability to delete packages from the /var/satellite directory which does now match with the checksum on the database. 

This is very useful when having RPM files corrupted.

Running this command with # spacewalk-data-fsck -f -R  clean the corrupted RPM files. Afterwards, satellite-sync we re-download it. 

If committed, I'll send a new patch adding this option to the man page  (see https://github.com/spacewalkproject/spacewalk/pull/29)