updated the processSeries method to not remove the navigator series that...

The processSeries method is removing the auto generated series that is added to the chart when using a separate data set for the navigator like so:
```
options: {
	    navigator: {
	    	series: {
	    		data: [/*some custom navigator data*/]
	    	}
	    }
}
```
This was causing the navigator to be be blank.