Some notes on contributions.

Life after switching to the core components of ROS to github has
dramatically improved the rate at which patches are being produced and
accepted and I think we will really see the benefits of this in the next
few releases.

I also want to note that if you submit an issue to the tracker on github
and your bug is marked for an Untargeted Milestone this means "Patches
and external contributions are welcomed and will be reviewed for release
if submitted." This is a great way to determine if no one else is
already working on fixing your problem.