Refactor from custom serial to a Serial ros package

[btdubs]

To get Rigatoni set up quickly, we copied IGVC's Yost IMU code which required the Serial package. To be consistent, we should move all of our Serial code over to that package instead of our custom Serial code.

IGVC uses the same Yost IMU, so you can move the serial interface and yost imu code to rj_ros_common.

Code touched will be all our car's motor relays at least.

[oswinso]

If you're copying our Yost IMU code, then copy the ones from this pr instead of the one on master, because we copy-pasted ours from master and its shit

[oswinso]

Also, I think since we're both using the Yost IMU and it seems like we're both copy pasting this code, I think this would be a good opportunity to put this in rj_ros_common so we don't have to like fix the same issues / add the same features twice.

[btdubs]

Good point. I'll update the issue to reflect that. That pr reminds me we also need to implement the diagnostic system to clean up a lot of the terminal spam.