* Moved FrameworkNode to nGraph
* Moved graph comparator to ngraph test util
* Fixed build
* Try to fix centos
* Fix export target
* Moved engine utils to separate library
* Removed ONNX util from common library
* Fixed build
* Fixed code style
* extract SpaceToDepth implementation from op class to reference file
* move backend test from fused_op.in.cpp to space_to_depth.in.cpp
* Cleanup reference implementation
* Extend SpaceToDepth backend tests
* add SpaceToDepth to verified ops