ROS 2 Foxy Release

[DLu]

Related to ethz-adrl/ifopt#66 it would also be nice to have a ROS 2 release.

For my purposes right now, it'd be sufficient to have just towr released (which shouldn't take too much work) and leave porting towr_ros and xpp for later.

[DLu]

@awinkler What do you think about this one? Would you be ok with releasing this to foxy without towr_ros?

[awinkler]

Sure, I added you as maintainer (y), feel free to release for foxy, even without towr_ros.

[YumingChennn]

I hope this message finds you well.
I am currently developing a project involving a four-legged robot and have two question:

1. Can Towr be used with the ROS2 Foxy version now?
2. Is there a README or guide available for downloading for Foxy version?

Thank you very much for your assistance.