combine ng-ckeditor with jquery ui sortable

[solverat]

Its not a pure ng-ckeditor issue, but we need to get rid of this:

if you are using an ckeditor nested in a sorted field, ckeditor will fall apart. This is a known issue, but i can't find a solution in combination with ng-ckeditor.

in fact, we need to:

1. onSortStop => destroy all ck instances
2. onSortStop => reinit all ck instances