Bug 1050097 - [Camera] Add error handling while |videoStorage.addNamed| occurs error.

@dmarcos , thanks for your suggestion, but I didn't get it.
As I understand, should I add new callback function named ```createVideoFilepathDone``` just like this:
``` javascript
self.createVideoFilepath(createVideoFilepathDone);
function createVideoFilepathDone(errorMsg, filepath) { 
  // do something for done
}
```
Am I right? Could you tell me more?
Thanks.