Bug fixes

Hi,

There're two problems that prevent creating and publishing a path on a fresh installation:
- The resource voter needs a resource node to perform its check, but when opening the path tool, no node is available.
- The description field is mandatory for generated activities, but the path manager accepts an empty description.

This PR offers quick fixes for these problems. The first one has no real solution, so I chose to bind the right to create a path via the path tool to the manager role of the workspace.