Feature/scenario stops

This adds the ability to add/delete stops in scenarios

![Uploading 3.png . . .]()

![2](https://cloud.githubusercontent.com/assets/1977405/4955361/ba32bd24-6694-11e4-872c-86f08c873c29.png)

Since this creates a StopTime, should add the following in this module:
```
function OTIStopTime() {
    this.id = getId();
    this.arrivalTime = '';
   ...
}
```

Then new an instance in the stopTimeFromLayer function.