Add the fieldIdentifier to renderField exception message

Not a bug but something that may help a bit in your dev process. 
Actually, when trying to render a field not present in a content, the exception message we get is like 
```
An exception has been thrown during the rendering of a template ("Argument '$fieldIdentifier' is invalid: Invalid for content #526...
```
This patch just change single quotes for double quotes so we can get the missed field in the Exception. 

Don't think this needs a issue in the tracker but let me know if you prefer me to do it.