Introduce new frontend for Caffe

[zhupijuan_lkl]

@lixiaoquan

A protocol message was rejected because it was too big (more than 67108864 bytes)

There are two mothods to solve this problem.:

1. follow the suggestion as error log: increase memory limits at CodedInputStream::SetTotalBytesLimit() and re-compile protobuf
2. upgrade protobuf into >= 3.2

Hope to help you