Figure out better quick attach plate mechanism

[dbenamy]

We tried to use a minimal quick attach mechanism to attach the backhoe 3 to the lifetrac 6, but the connection was way too lose and unsteady. After a slightly jerky motion of the backhoe, the whole thing popped off the quick attach fingers.

There was also a problem where the backhoe may sometime experience forces which push it up, and the way we had the QA mount set up, this would try to force it off the QA fingers.

We wound up not using the QA mount for now and bolting the backhoe to the tractor until we can figure this out.