changed request url to match real parameter

Fixes critical bug, which loaded the wrong webspace in the column tree view.

- [ ] test coverage
- [ ] finish the code
- [ ] gather feedback for my changes
- [ ] submit changes to the documentation


| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| Tests pass?   | none
| Fixed tickets | #72 
| Doc           | none