The default `date_select` used in fields presents an accessibility
issue, because in generates three select controls but only one label.
That means that there are two controls without a label.
So we're using a date field instead. This type is field is supported by
about 99% of the browsers, and we've already got JavaScript code
converting this field to a jQuery UI datepicker in case the browser
doesn't support date fields.
Note that, since we no longer need to parse the three date fields into
one, we can simplify the code in both the models and the tests.
Another slight improvement is that, previously, we couldn't restrict the
month and day controls in order to set the minimum date, so the maximum
selectable date was always the 31st of December of the year set by the
minimum age setting. As seen in the component test, now that we use only
one field, we can set a specific date as the maximum one.
We were very inconsistent regarding these rules.
Personally I prefer no empty lines around blocks, clases, etc... as
recommended by the Ruby style guide [1], and they're the default values
in rubocop, so those are the settings I'm applying.
The exception is the `private` access modifier, since we were leaving
empty lines around it most of the time. That's the default rubocop rule
as well. Personally I don't have a strong preference about this one.
[1] https://rubystyle.guide/#empty-lines-around-bodies
Here's a better alternative than the first one. Added a new abstraction level from which are performed both types of census calls, while the logic of those is managed in their own library.
