chore: remove form_field.isFutureOnly key

[tshuli]

Problem

Closes #40

Tests

Create 5 date fields in admin view with the following options. Test that the validations work in the preview panel datepicker on the right (i.e. the popup calendar).

• Disallow past dates
• Disallow future dates
• Custom date range with Min Date only
• Custom date range with Max Date only
• Custom date range with both Min and Max Date

Validation for date range validation option in admin view

• Check that it is not possible for admin to save a form with a custom date range where both Min and Max date are left blank
• Check that it is not possible for admin to save a form with a custom date range where Max date is before Min date

Able to submit forms correctly

• Publish the form. Test that all 5 date field validations still work in the public form datepicker (i.e. the popup calendar)
• Test that all 5 date field validations still work in the public form using manual input to the date field and manual input of date outside the validation range is rejected

Test for editing and reordering, instead of creating

• Using the existing form fields, shuffle the form validations of the five fields by editing the validation options
• Reorder the form fields
• Repeat the above tests to make sure the date validations remain correct

Scripts

• DB script in remove-isfutureonly-key.js, to be run one week after release

[mantariksh]

could you also include a db script to remove the old key? as recent experience has shown, we should avoid leaving old keys dangling

[karrui]

Have you been committing with --no-verify? That defeats the point of hooks :/.

[karrui]

Some changes, I'll leave it to @mantariksh to really review the script ><

[mantariksh]

lgtm

[karrui]

Sorry for the many separate comments, basically just try again on localhost and see if any errors pop up

[karrui]

lgtm