Add basic progress bar for identity
Extract Progress concern and include for all models

The generic Progress concern will estimate progress for a model, and
those methods are used to fill the progress bars on each edit screen.
Add a "Save" button that reloads the same object
Person progress includes mail_address progress
Rename Progress methods for consistency
Declare progress submodels with Progress::progress_includes

Instead writing this in the models:

    def progress_includes
      [:mail_address]
    end

We can now write this:

    progress_includes :mail_address
Fix Income#to_s for nil income_type
Fix CriminalHistory#to_s for nil year
Add progress_includes to employment and residence
Fix income rendering issues for applicant show page
HouseholdMember progress includes :person
Add progress for Applicant, including associated collections

Fixes #104
Show progress badges on tab dropdowns

For #104.  Includes a big refactor of _section_tabs.html.erb