Fixed editor crash after deleting a table

This is a fix for a bug.

**Scenario:**
1. Have an inline initialized editor
2. In that editor add a table and ensure that it is the sole element in the editable container (nothing before and nothing after)
3. Use the contextual menu to delete the table
4. The editor is no longer working :(

*Note: This can be reproduced also on the demo site: http://ckeditor.com/demo#inline*

**The fix:**
Just added a check to not remove the parent element of the table if that parent is the container.