Added ARDUINOJSON_ENABLE_NAN to enable NaN in JSON (closes #973)

test/MixedConfiguration/CMakeLists.txt

@@ -12,6 +12,8 @@ add_executable(MixedConfigurationTests
 	use_double_1.cpp
 	use_long_long_0.cpp
 	use_long_long_1.cpp
+	enable_nan_0.cpp
+	enable_nan_1.cpp
 )
 
 target_link_libraries(MixedConfigurationTests catch)