test=develop

* feature/buffer_shared_inplace, test=develop

* refine code, test=develop

* fix elementwise_add op cpu inplace and sum inplace bug, test=develop

* add unittest and debug log, test=develop

* fix parallel_executor scope bug, polish code, test=develop

* fix sum op, activation op, single_in_place_inference bug, test=develop

* remove kLocalExecScopeName, test=develop

* fix unittest,test=develop

* fix out_var first version bug, test=develop

* follow comments,test=develop

* add event for fast executor and add threads for scopebuffer executor
test=develop

Refine the Executor when the num_thread=1

* speedup gc and inplace softmax_with_cross_entropy_grad
test=develop

* refine models gpu mem
Merge skip vars and warning messages of mem opt
remove relu mem opt
test=develop

* follow comments
test=develop

* Fix the bug of the fast threaded executor. I

* fix threaded executor bug
test=develop

* change the order of class member
test=develop

* Fix Travis CI
test=develop

* Unified ParallelExecutor and Compiler

* Unified ParallelExecutor and Compiler

test=develop

test=develop

Dry run tests will skip `Op.Run` and just perform job scheduling. It helps to analysis dead lock in PE.

test=develop

test=develop

test=develop

test=develop

It seems that the blocking queue might be destroyed early than Run
method complete. It might because the Run method throw some unhandled
exception. However, it should be shared_ptr when multthread access an
resource. So change BlockingQueue as a shared_ptr.

test=develop

    Node should be created by Graph::CreateXXX so that
    they are managed by graph.