Support for dynamically sending to multiple Graphite clusters

[spil-sean]

I think it would be useful to be able to send graphite data a system of choice. So Production / Staging/Dev can be separate graphite clusters to be be sent to.

Determining which to send to could be handled by a custom macro, much like the PRE/POST fix for metrics.
New modules could perhaps use something like tags to accept measurements

[naparuba]

Good idea I like it :)

[naparuba]

I reopen the ticket on the new graphite repo : shinken-monitoring/mod-graphite#1