cpu-idlefix: import version from munin 2.0.6
cpu-idlefix: look at kernel version

Look at the major kernel version number to decide whether to fix idle or
not.

Now the graphs are still correct, even when running squeeze with a newer
3.x kernel.
rename cpu-idlefix to cpu

keep cpu-idlefix as symlink until migrations are done
cpu: don't use upper limit in graph

when rebooting with less cpu than before, I still want to see the old
(higher) values in the graphs instead of having them cut off at the
current cpu limits
Merge branch 'master' into debian for release 0.5
Update changelog for 0.5-1 release