dded GB/VI to Cuda platform

Free energy plugin added
Plugin will not run w/ Obc or GB/VI forces unless line 2004 of gpu.cpp (gpu->sim.totalNonbondOutputBuffers  = 2*gpu->sim.nonbondOutputBuffers;) is commented in -- working on removing this constraint
Also unit tests for GB/VI currently fail 

plugins/freeEnergy/platforms/cuda/staticTarget/CMakeLists.txt

+#
+# Include CUDA related files.
+#
+SET(OPENMM_BUILD_FREE_ENERGY_PATH ${CMAKE_SOURCE_DIR}/plugins/freeEnergy)
+
+SET(CUDA_NVCC_BUILD_FLAGS "-DCUDPP_STATIC_LIB" )
+INCLUDE(${FINDCUDA_DIR}/FindCuda.cmake)
+INCLUDE_DIRECTORIES(${CUDA_INCLUDE})
+LINK_DIRECTORIES(${CUDA_TARGET_LINK})
+FOREACH(subdir ${OPENMM_SOURCE_SUBDIRS})
+    FILE(GLOB src_files ${OPENMM_BUILD_FREE_ENERGY_PATH}/platforms/cuda/${subdir}/src/*.cu  ${OPENMM_BUILD_FREE_ENERGY_PATH}/platforms/cuda/${subdir}/src/*/*.cu)
+    FOREACH(file ${src_files})
+        FILE(RELATIVE_PATH file ${OPENMM_BUILD_FREE_ENERGY_PATH}/platforms/cuda ${file})
+        SET(SOURCE_FILES         ${SOURCE_FILES}         ${file})   #append
+    ENDFOREACH(file)
+    CUDA_INCLUDE_DIRECTORIES(BEFORE ${OPENMM_BUILD_FREE_ENERGY_PATH}/platforms/cuda/${subdir}/include)
+    CUDA_INCLUDE_DIRECTORIES(BEFORE ${OPENMM_BUILD_FREE_ENERGY_PATH}/platforms/cuda/${subdir}/src)
+ENDFOREACH(subdir)
+#CUDA_INCLUDE_DIRECTORIES(BEFORE ${OPENMM_BUILD_FREE_ENERGY_PATH}/jama/include)
+CUDA_INCLUDE_DIRECTORIES(${OPENMM_BUILD_FREE_ENERGY_PATH}/platforms/cuda/../src
+                         ${OPENMM_DIR}/platforms/cuda/src
+                         ${OPENMM_DIR}/platforms/cuda/src/kernels
+                         ${OPENMM_DIR}/openmmapi/include ) 
+
+CUDA_ADD_LIBRARY(${STATIC_TARGET} STATIC ${SOURCE_FILES} ${SOURCE_INCLUDE_FILES} ${API_ABS_INCLUDE_FILES})
+
+# required for getting OPENMM_EXPORT to be set correctly in 'class OPENMM_EXPORT CudaStreamFactory', ...
+# see OpenMM/openmmapi/include/internal/windowsExport.h for details
+
+SET(CUDA_STATIC_COMPILE_FLAG "-DOPENMM_BUILDING_STATIC_LIBRARY -DOPENMM_USE_STATIC_LIBRARIES -DCUDPP_STATIC_LIB")
+SET_TARGET_PROPERTIES(${STATIC_TARGET} PROPERTIES COMPILE_FLAGS ${CUDA_STATIC_COMPILE_FLAG})
+
+TARGET_LINK_LIBRARIES(${STATIC_TARGET} optimized ${OPENMM_LIBRARY_NAME}_static)
+TARGET_LINK_LIBRARIES(${STATIC_TARGET} debug ${OPENMM_LIBRARY_NAME}_static_d optimized ${OPENMM_LIBRARY_NAME}_static ${CUFFT_TARGET_LINK})
+
+INSTALL_TARGETS(/lib/plugins RUNTIME_DIRECTORY /lib/plugins ${STATIC_TARGET})