implements fix for wall boundary conditions

src/GksGpu/BoundaryConditions/BoundaryCondition.cpp

src/GksGpu/BoundaryConditions/Pressure.cu

src/GksGpu/DataBase/DataBase.cpp

src/GksGpu/DataBase/DataBase.h

src/GksGpu/DataBase/DataBaseAllocatorCPU.cpp

src/GksGpu/DataBase/DataBaseAllocatorGPU.cpp

src/GksGpu/DataBase/DataBaseStruct.h

src/GksGpu/FluxComputation/FluxComputation.cu

src/GksMeshAdapter/MeshCell.cpp

src/GksMeshAdapter/MeshCell.h

src/GksMeshAdapter/MeshFace.cpp

src/GksMeshAdapter/MeshFace.h

targets/apps/GKS/ChannelFlow/main.cpp