setRowMetadata not working

Cannot get row metadata to work as per wiki:

```
grid.behavior.dataModel.setRowMetadata(1, { lastName: { color: 'red' } });
grid.behavior.changed();
```
__META is set but grid throws an error:
**_Cannot read property '0'_ of undefined** in **assignProps** in layer-props.js
```
propLayers = cellEvent.properties.propClassLayers; \\ this is undefined
```
Trying to hack this doesnt really help much; just propagates the errorr; ended up having to add the below which resulted in empty cell rendered... where exec is the exec from defaults
```
grid.behavior.dataModel.setRowMetadata(1, { lastName: { color: 'blue', propClassLayers: [1,4], exec: exec, grid: grid ,renderer: 'SimpleCell' }})
```

I can see that META object set using cellEventPool from renderer is much richer and works fine.