Fix bike.js array push issue.

A reference of the same object is being modified and passed to setCoords. This would cause the _coords array to look like it has duplicates, but really, each item in the array is just a reference to the same object.

Example:
```javascript
var arr = [];
var obj = {x:1};
arr.push(obj);

//getLastCoords returns the last pushed coords obj.
var last = arr[arr.length-1];

// but its the same obj..
last == obj; //true

```

Fix by creating a new object to be pushed into the array.