Two fixes:
1) Use same regexp to skip df partitions in "config" and "fetch".
2) Use same function (was two different sed) to cleanup partition name.
This fixes bug #5.
Previously MuninLite tried to create a drop-in-replacement for
munin-node by using the same name. But MuninLite behaves differently
and may even be used in parallel to a regular munin-node setup on a host,
thus it should use a distinct name.