Add type="time" to timeField

I noticed that most forms use a specific input type (e.g. `intField` uses `type="number"`), but `timeField` didn't use  `type="time"`. Probably it was just an oversight to leave it out?

Here's how it effects the browsers I tried it on:

* Chrome: Upgrades from a free-form text field to a text-field that validates input and jumps between the Hours/Minutes/(AM/PM) fields
* Firefox: Unchanged from free-form text field
* Safari: Unchanged from free-form text field
* Mobile Safari: Upgrades to iOS's time selector

As I was submitting this PR, I realized that the existing input supports an optional seconds value according to `MsgInvalidTimeFormat`, but Chrome and Mobile Safari don't allow inputting seconds when you use `type="time"`, so possibly type="time" was intentionally left off to support this?