title: Timezone support with date-fns
body: <p>I'm considering migrating my project using <code>moment</code> into <code>date-fns</code> which is known as simple, functional etc. But after I played with it a while, I noticed they don't support <code>timezone</code> yet. They have introduced <code>locale</code> and <code>timezone</code> option in <code>format</code> and other functionality in alpha 2.0.0 lately but the <code>locale</code> option is just a language support and the <code>timezone</code> option in those functions just shows/adds the <code>GMT</code> sign(ex. 2018.08.29 GMT+9). So I was wondering if I'm just missing it although they already support it or they really haven't supported it yet.</p>