Prevent warnings from external include directories.

CMakeLists.txt

@@ -30,7 +30,7 @@ if (ASSIMP_FOUND)
   else()
     message(STATUS "Assimp version does not have unified headers")
   endif()
-  include_directories(${ASSIMP_INCLUDE_DIRS})
+  include_directories(SYSTEM ${ASSIMP_INCLUDE_DIRS})
   link_directories(${ASSIMP_LIBRARY_DIRS})
 else()
   message(STATUS "could not find assimp (perhaps available thorugh ROS package?), so assimping assimp v2")
@@ -204,7 +204,7 @@ include_directories(SYSTEM
   ${OPENGL_INCLUDE_DIR}
   ${PYTHON_INCLUDE_PATH}
 )
-include_directories(src ${catkin_INCLUDE_DIRS})
+include_directories(src SYSTEM ${catkin_INCLUDE_DIRS})
 
 #### If gtk ends up being the best way to get the correct window
 #### position under X11, this is how to compile it in.