Ceph

Add a ceph plugin based on (https://github.com/ceph/collectd): 

1.Correct commands used to fetch data from ceph side,make it work for latest ceph
2.Fix issue that cannot create rrd output due to invalid DS name.
3.Fix issue that always produces zero value for DS.
4.Dispatch Data Srouce to separate Data Set instead of dispatching all of Data Srouce to one Data Set.