deferred in location validation

### Done
* Now using deferred instead of callbacks in location validation.
* Replaced alert for error message.

### Todo
* Merge with payment when pull request on [nice alerts](https://github.com/osylvain/laconfrerie/pull/14) is merged

well .. some might say that you should export objects and some would say you should export functions when you can ..

I'm part of those who say 'write functions not class' so.. in this case you would directly export the validateDestinationIsIsBound function just like it was... 
In this case there is not so many difference ..