Automatically add a class to an html tag

[egrefin]

Hi,
How do I automatically add a specific class to an html tag?
For example, I'd like to add class="img-responsive" to each img tag when I insert an image in the editor.
With CKFinder/CKeditor, you can do this as follows:
ev.editor.dataProcessor.htmlFilter.addRules( {
elements: {
img: function(element) {
element.addClass('img-responsive');
}
}
});
Is there an equivalent?
Thanks!

[egrefin]

Okay, I found the solution.
It's in the editor (TinyMCE) and not in the file manager.
Sorry.