Revert "bugfix for #1098 (assigning a group to a user, the group appears incrementally many times the more you assign it)"

This reverts commit 265d7e50.

- when creating a new text file or directory which name already exist use the same pattern as for file uploads in such a case (add a (N) to the name)
- don't allow renaming if a file/directory with the name already exists

- if secure is set to true add 's' to http