Created by: sunxl1988

gpu: one P40 faster rcnn(batch size 1): 0.298 <-> 0.336 (previous) yolov3(batch size 8): 0.1883 <-> 0.201 (previous)

add prefetch for data loader split config yml into 3 parts (reader, architecture, optimize) add increment config method

adapt mask rcnn & mask rcnn fpn