Fixing tftpboot path and post-build cleanup, add Ceph RPM build

Changes to the RPM build process for the opencrowbar-core-discovery RPM so root-owned intermediate build files  get removed - we want to leave our build environment as clean as it was before we did the build.

Fixed location of the tftpboot files so it works with paranoid tftpd configuration.

Added RPM spec file and build capability for the new opencrowbar-ceph RPM.