[collectd] New aggregator plugin "basic_aggregator" (#136)

[Fabien Wernli]

Hi,

Adding a configuration reload is an excellent idea, and is one of the big
missing features of collectd IMHO. I quite agree with Lindsay's remarks:
there should simply be a warning for the plugins that don't support
reconfiguration. On the other hand, maybe there should be the option to
restart the thread, if it doesn't register the cb.

just my 2 euros

Cheers