* update anakin-engine interfaces for content-dnn

test=develop

* support only-gpu mode of Anakin

modify eltwise parse

test=develop

* modification for thread-safe

test=develop

* Integrated template instance

test=develop

* increase template parameters

test=develop

* support MLU predictor

test=develop

* update anakin cmake files

test=develop

* update TargetWrapper::set_device

* update the initialization of anakin subgraph

test=develop

* use the default constructor of base class

test=develop

* anakin support x86

* fix code style

* add anakin ditu cnn demo

* add timer

* add rnn

* fix inference_anakin_cnn/rnn_test compile error

* make anakin_rnn_tester run

* add anakin_enable_op_time option

* update api/CMakeLists.txt

* enlarge the max_batch_size in anakin.config

* update with comments