python 3 compatibility
update changelog
"0.4.15"
fix warning about empy message definition (fix ros/ros_comm#344)
Merge pull request #14 from ros/fix_empty_msg_def

fix warning about empy message definition (fix ros/ros_comm#344)
update changelog
0.4.16
Merge https://github.com/ros/gencpp into groovy-devel