Debug observe

There is an extra ```observe``` that crashes translation when using the directive in "non-attribute-content-mode" when ```translationValue``` is empty.

```setupwatcher.done``` in then set and when ```observe``` triggers again (by the ```scope.$watch```), the element's content interpolation cannot work anymore.

Removing the extra (and unnecessary ```observe```) corrects this behavior and removes unnecessary overhead.

It means also that the observe function is run systematically only by the watcher, so I had to add some kind of delay in the tests in order for the ```$digest``` phase to run. ```$rootScope.$evalAsync``` should be best for that. :)