Removed __call__ methods of aggregators.
Removed __call__ methods of aggregators.

Confusing, and documentation hidden. Redundant anyhow.

datreant/datreant.core,datreant/datreant.core,datreant/datreant,datreant/datreant,andreabedini/datreant,datreant/datreant.data,dotsdl/datreant