allow setting of graphite options

gmetad now support pushing stuff data directly to carbon aggregator.
I added the setting to gmetad so you can set them in the gmetad.conf

also this one sneaks in a change so you can set `write_rrds` as well (by default it should behave the same way as master).  For some reason someone may want to disable rrds.
I implemented an alternate of check at the template level, so one doesn't have to say 'enable graphite AND here are the configs'