Expose API to allow bulding on top of the plugin

[yonjah]

It would be great of some of the api was exposed so we could programmatically call methods and run commands. I mostly think of a command runner similar to what toolbar click handler is doing only with a generic command and value

runCommand(command, value) {
            self.restoreSelection(  );
            editor.focus();
            self.execCommand( command, value, editor, options, toolbarBtnSelector );
            self.saveSelection( );
}

This will allow more flexibility and custom ui when calling commands (like poping up a dialog to enter url)