correctly assign left and right gps serial ports

[pearlastrid]

Summary

Closes #655

What features did you add, bugs did you fix, etc?

On gps_driver node init finds gps usb devices and sends poll request for a configuration variables differentiating the left and right gps. Changes ros "port" param for left and right gps accordingly.

Did you add documentation to the wiki?

Yes/No (If not explain why not)

How was this code tested?

Summarize how you tested this code. Your objective here is to prove to the reviewers that this code actually works without them having to run it themselves. It is often helpful to include screenshots, tables, graphs, and/or a short write-up of testing procedures. Results can be either from sim, the robot, or both depending on what you think is sufficient for the feature you added.

Need to test on jetson with the new udev rules, have not had the chance to yet

Did you test this in sim?

Yes/No

Did you test this on the rover?

Yes/No

Did you add unit tests?

Yes/No (If not explain why not)