Fixes: few changes

1. Fixed jquery data-attributes: data('projectId') instead of data('project_id') in projects.js
2. Fixed tasks lists in project controller actions: update_icebox, backlog, current_work, my_work (was :tasks => project.icebox, but need project.tasks.icebox, because we moved scopes into tasks from projects)
3. Added manage to Task model ability (tmp solution for make master live).