Fix moment.js deprecation warning

[Frozenfire92]

This occurs due to a future deprecation in moment.js. See issue

Deprecation warning: moment construction falls back to js Date. This is discouraged and will be removed in upcoming major release. Please refer to https://github.com/moment/moment/issues/1407 for more info.

[adamcee]

Hi. I am encountering this issue. New to working on open-source so forgive any etiquette mistakes on my part.

When attempting to solve this issue using javascript moment(someDate).isValid() and get rid of the deprecation warning, I tried:

moment(someDate, moment.ISO_8601).isValid() 

...and still received the deprecation warning. It seems like the deprecation warning should not occur in this case. Also this could be a good use case for general date validation with the stricter moment.js

[duizendnegen]

we could move towards only exposing moment dates or use http://momentjs.com/docs/#/parsing/string-format/
fortunately moment objects are cloneable, ref. http://momentjs.com/docs/#/parsing/moment-clone/ - means that we can move internally to make everything moment objects without breaking outside behavior

[Frozenfire92]

Hi @adamcahan and @duizendnegen

I've been swamped with school lately and haven't had a chance to look into this issue. Thanks for your responses and if I don't get to it sometime soon feel free to submit a PR!