* Add MKLDNN layout support in Paddle

Add MKLDNN layout in Paddle so that MKLDNN friendly memory layout
can be used in MKLDNN enabled OP kernel. Before this commit, NCHW
is hardcode to be used in all MKLDNN op kernels. As a result,
non-optimized execution path is selected in MKLDNN primitive which
bring worse performance.
Besides framework change, three MKLDNN OP kernels were updated
for using new MKLDNN layout. They are conv/pool2d/batch_norm.
Other MKLDNN OP kernels need be also updated in similar way to
achieve best performance.

* Add MKLDNN layout support in activation OP

* Don't populate layout from input to output when kMKLDNN in

* Refine pool mkldnn op kernel

* MKLDNN layout

* Remove the inferitance from tensor file

* MKLDNN layout: refactoring

* Remove additional #define to register new operator

* Prepare mkldnn tests to work with layout

fix a compile error on Mac

[Feature] Add fuse vars op handle

rewrite unittest of trt_activation_op

Add unittests to check channelwise add

Add reverse op

install libgtk2.0-dev in latest images

SSA Graph Builder Factory

Extract method from tensor_impl.h to tensor.cc

Fix formula display error

fix cudnn version issue

Fix abort issue in cpu multi-threads

add python-opencv in paddlepaddle/paddle:lastest images

* Enable assertions in CUDA.

* Fix PADDLE_ASSERT.

Merge remote-tracking branch 'ups/develop' into multithreads

* Use Builder Chain to decorate new builders. It is easy to extend
  builders.
* Make graphviz path as a build strategy, not a FLAGS.

small clean up and document pointer ownership.