fix: fix @typo in name_search method
New: turn product backlog stages like task stages for a better @usability:

- Stages are no more linked to only one project
- You can select which backlog stage you want by project (on project form)
- Stages can be set as default for new project
- Fix sequence on tree view.
Merge pull request #3 from njeudy/project_backlog_stage

Project backlog stage