This Fixes #864,#827 - up/down arrow interference

Disabling up and down arrows for both comment text area edit and on content editable.
Yah I had done that initially when I saw you had mentioned that we can disable it . Then I thought as if it will impact anything else so gave this fix. Even I too agree that we should not touch the lib files as tmw we might upgrade these libraries to newer versions and we don't want to do that. But I thought that already the tree.jquery.js has been altered. 
Anyways I will change the impl. My inital fix was this which I never comitted:
$tree_.tree({
                data: data,
                onCreateLi: on_create_tree_li,
                selectable: true,
                keyboardSupport :false
            });
I think you are also asking me to do the same.