Add clear errors

[kenconnor]

Taking over https://github.com/odriverobotics/ros_odrive/pull/14 The former PR broke file structure and I made a brand new PR.

I tested it on S1. I called /request_axis_state with wrong state, called /clear_errors and then called /request_axis_state with correct state. I confirmed that procedure_result is changed to 0.

[kenconnor]

I think S1 needs to call clear_errors() to re-enable the brake resistor, but under what circumstances is the brake resistor disarmed? Since I use S1, I would like to enable and use the brake resistor if it is disabled.

I made the following edits:

• Removed whitespace unrelated to the PR from the commit
• Added to the README

I was concerned that the contribution of liborw in #14 might disappear, so I decided not to consolidate the commits to preserve the commit history. Should we consolidate all changes, including the additions to the README, into a single commit (add service to clear errors)?

[kenconnor]

@samuelsadok I have made the following changes:

• Squashed original commits
• Left Libor as a co-author
• Changed the sentence in README

[samuelsadok]

looks good, thanks!