Add functionality for School/Department for an organisation. ...

Changes:
    - added a Department model whose instances belong to an org and require name.
    - added a DepartmentController and views for create, edit/update and a index view which is a tab
      of 'Organisational Details'.
    - added the optional attribute department_id to User model.
    - added Rspec tests.
    - updated app/controllers/registrations_controller.rb, app/models/org.rb and
      app/models/user.rb to get rid of outstanding Rubocop warnings

    Fix for issue #2088.

1. stat_created_plan.to_csv with option for details by template. ...

2. details attribute for stats table #1679
3. create_created_plan_service extended with details by template
4. create_last_month_created_plan_service extended with details by
template.
5. create_or_update strategy for generating stats
6. StatCreatedPlanByTemplateController#index for graphs usage
7. month_start_date and month_end_date for OrgDateRangeable class

[RD-1679] Usage view including date input for plans by template

[#1679] monthly_range query updated

[#1679] client-side chart for plans by template

[#1679] Time picker for plans by template chart

[#1679] Download plans by template action.

deleted spec

merge conflicts fixed

[#1679] Removed JS linter warnings

[#1679] Rubocop conforming code. Drying out stat services

Merge pull request #1989 from DMPRoadmap/issue-1161 ...

Issue #1161 - Display tooltip below form fields on Create plan page.