Related#1908

cc@vapurrmaid (some of these are taken from the PR)

1. Allow setting "Days of Week" when "Start time" is unset
   • This one confused me. We shouldn't assume that users will fill out the form in top to bottom order.
2. Timezone should be select list, then we can avoid the user education. Also: why does time zone have a dashed border instead of a solid border?
3. Timezone should default the the browser's declared time zone
4. Clock icon blends in with background. Lighten it.
5. Rewrite "TTL" for clarity (see screenshot)