* add crop and reduction layer
* caffe2fluid: support crop and reduction layer convertion

* caffe2fluid: fix bug in leaky-relu and add interface for prelu convertion
* caffe2fluid:fix code style problem in graph.py

support multiple data layer;
fix bug about caffe_pb2;

caffe2fluid: support Reshape and Scale convertion; fix bug in dropout; add more tools for comparing results (#880)

* fix code style problems

* fix bug when loading fluid model

* fix code style problem in brain.py

2, add examples for imagenet and mnist
3, support new operator: dropout, lrn, concat
4, compatible with old versions of caffe
5, fix bugs