Firmware version included in message or new topic

[icolwell-as]

I think it would be very helpful to have the PACMod firmware version published to an existing topic or to some new topic.
This way a recorded rosbag always has PACMod firmware version already included.

[JWhitleyWork]

This first requires a change to the DBC (and firmware) to transmit the version. This is underway in astuff/pacmod_dbc#10. Once that issue is implemented, I'll follow up with relevant changes to the driver.

[JWhitleyWork]

@icolwell-as - This is now available in the DBC and will be published by newer versions of the firmware (see astuff/pacmod_dbc@f785a2c). Would you mind implementing it in the driver?

[icolwell-as]

Sounds good! I might not get to it for a while, but I'm interested to learn more about this driver in the process.