APICaffe: need something to replace heproot

[drinkingkazu]

We need:

*) Threaded read-and-process method
*) Ideally runs ProcessDriver so we can attach Process and execute on the fly
*) Need base class to define how to fill datum (i.e. hand over data to caffe)

[drinkingkazu]

#6 is going to be the actual implementation of this.

[drinkingkazu]

Pushed, seems to work fine. One can test:

run_filler.py filler.cfg

... though you need relevant input files (see filler.cfg)

[drinkingkazu]

next: need implementation in caffe fork

[drinkingkazu]

done: 302f1fa