Things left todo:

• Fix the remaining warnings (currently 3) on OS X: http://54.183.26.131:8080/job/ros2_batch_ci_osx/156/warnings7Result/
• Audit and fix warnings for Windows (currently 1380 warnings)
• Use a narrower warning suppression with rmw_opensplice and rmw_connext: fix warnings rmw_connext#40 (comment)