Add OpProto implementation

Fix style check

Using glide for go package vendor

Go optimizer: integrate Go with optimizer library

OpProto is a proto message that helps 3rd-party language bindings, e.g.
`Python`, to generate operator creation methods. The operator creation
method is the low-level API for 3rd-party language bindings. Op creation
methods take the user's input in that language, and convert users inputs
into `OpDesc` message, then passing that `OpDesc` message to Paddle's
C++ core and create an operator.

* A separated `attr_type.proto` is added, because that file wound
  be included by `op_desc.proto` in future.

[draft] a simple op design doc

Add tensor.h

Fix bug for flowers dataset and row_conv.

fix input shape of train_y in get started doc

Design doc: save model in cluster training.

ENH: support command `make target_name`

fix the bug of copy master directory.

NNPACKConvFunction

FIX: Replace static libs check via system warning

Add the use_nnpack parameter in ExpandConvLayer, so that the convolution calculation can be switched to the NNPACK function.