Change board's ready trigger timing

Thanks for your work ecto, duino is really cool and easy to get into, good job!

Anyway, this PR fixes #21.

It was a sort of racing condition where the board would sometimes trigger the `ready` event earlier and it should, now it listens for serialport's `open` event.
Also I made it so that you can use servos inside the board's `ready` event callback.
Lastly updated the board's name property to `path` based on serialport's.

Cheers