change tabs size to 2

CMakeModules/astyle.cmake

@@ -8,7 +8,7 @@ if(ASTYLE_EXECUTABLE)
 		COMMAND
 		${ASTYLE_EXECUTABLE} -i
 			--exclude=${PROJECT_BINARY_DIR}
-			--recursive -n --style=google 
+			--recursive -n --style=google --indent=spaces=2
 			"${PROJECT_SOURCE_DIR}/*.cpp" "${PROJECT_SOURCE_DIR}/*.h"
 		WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
 		VERBATIM