Summary:
- Setting the locale in moment was not sufficient to actually use the
correct localized formats.
- Moment provides localized format via the formats : 'L', 'LL', 'll',
etc. See: http://momentjs.com/docs/#/displaying/format/
- Updates to set our date formats based on localized formats:
- Unfortunately, localized formats always contain the year, so I
manually removed the year from our short format.
- Actually fixes: #1515
- Fixes bug where setting nextWeek or thisWeekend returned incorrect
date if the current day was saturday or sunday
- Add specs
Test Plan: Unit tests
Reviewers: evan, drew, bengotow
Reviewed By: bengotow
Differential Revision: https://phab.nylas.com/D2688
