Removed deprecated ROS version check from generated boost headers in rtt_roscomm

Recent ROS versions don't need that check anymore.
`std_msgs/boost/Header.h` can be included like any other message type including the `boost/` path component.

Last but not least, `ros/common.h` is a roscpp header, but typekit headers should not depend on roscpp for the case typekits and ROS transports are used separately (although this is probably not yet possible...).