Incorporate humanised date helpers

[elisechant]

What I did

Following these guidelines for dates:

• http://content-style-guide.apps.staging.digital.gov.au/az-indexes/d.html#dates-and-time-periods
• http://content-style-guide.apps.staging.digital.gov.au/az-indexes/t.html#time

  What I expected to see

Ui-kit helpers or constant to format dates to these humanised strings.

such as:

const ISO_LONG_DATE = 'dddd D MMMM, YYYY';