- add naive executor
- fix concurrency performance issue

Use OO style to rewrite memory allocation.

* memory module

* "fix ci"

* memory init

* add env

* refine anounce

* Add check for Nan

* Debug

* Add env for cc_test

* Add env for py_test and nv_test

* Remove py_test env

* Add env for py_test

* serial test_recognize_digits

* Test FLAGS_init_allocated_mem function for unit test

* Init allocated mem for op unit test

* Add env for all unit test

* Fix cpplint errors with paddle/fluid/platform/gpu_info.*

* Update

* support empty tensor