* [Demo] add cxx mobilenetv1-ssd detection demo, test=develop

* add makefile to mobile detection demo, test=develop

* [Demo] add cxx mobilenetv1-ssd detection demo, test=develop

* [demo] fix mobile_detection code style, test=develop

* [Demo] fix demo code style, test=develop

* [Demo] fix detection demo makefile dependency, test=develop

* Add CheckInput. test=develop

* Fix android_log_ undef when using .a. test=develop

* add guide of how to use shared library in demo. test=develop

* Fix bug target for kHost and kARM not equal. test=develop

* Fix license. test=develop

* add debug -g option. test=develop

* enable opencl demo. test=develop

* Fix model_optimize_tool found no opencl kernel. test=develop

* add more vlog. test=develop

* remove macro LITE_WITH_OPENCL, LITE_WITH_FPGA in passes. test=develop

* Fix valid_places in mobilenetv1_test. test=develop

* Fix bug of find no real output of fetch, after tool OPs of optimzer passes. test=develop

* Fix vlog as log message in model_optimize_tool. test=develop

* fix miscs. test=develop

* fix comment. test=develop

* Fix misspell of opencl, fpga kernels name in lite/api/CMakeLists.txt. test=develop

* add opencl macro in full_api of demo. test=develop

* [framework][place] remove prefered_place, use place order in valid_place array instead test=develop

* remove kHost from valid_places test=develop

* Add precision and persistable attrs for the tensor. And fix cxx light and full api demo.

* update precision2string methods. test=develop

* move the save logic to the front of the run in mobilenetv1_full_api.cc, test=develop.

* add comments for UpdateVarsOfProgram. test=develop