Adding bidirectionnal binding with ngModel

I had a problem using ui-tinymce with ngModel because i binded my tinyMCE with a string fetched from a webservice. I have noticed that when the webservice response after that tinyMCE have render, the string does not appear.
Then I noticed that the binding is unilateral : a change from tinyMCE will be reflected on the scope, but a change on the scope won't be reflected on tinyMCE.
I made this fixe, i am new with AngularJS so it is probably a poor solution. 
I won't be surprise if you deny my pull request, but I wish you will fixe this bug.