[EuiSuperDatePicker] Clicking start/end inputs doesn't display the correct relative value

[formgeist]

When clicking the start/end range values, I’d expect the editor to show the value that was clicked - either as an absolute or relative value. Instead it just defaults to “0 seconds ago”. This usually happens with "commonly used" inputs i.e. month to date.

[cchaos]

It looks like it specifically doesn't understand the "Commonly used" items except for "Yesterday". Though most other cases work just fine.

cc @nreese

[nreese]

Looks like there is a bug in https://github.com/elastic/eui/blob/master/src/components/date_picker/super_date_picker/relative_utils.js#L10. Instead of parsing values of now/M, and grabbing the units, its just returning { count: 0, unit: 's', round: false }