v0.1.6 be able to have mkt-prompt part of the page, html5 validation

Should this be renamed to mkt-form? 

**\<mkt-prompt\>**

![screen shot 2014-12-22 at 11 24 59 am](https://cloud.githubusercontent.com/assets/674727/5529794/2f4ce3a4-89cd-11e4-9a4a-318ae27d3fc4.png)

**\<mkt-prompt data-modal\>**

![screen shot 2014-12-22 at 11 25 36 am](https://cloud.githubusercontent.com/assets/674727/5529801/42477faa-89cd-11e4-8aae-8fc0388ada06.png)

I really don't like this first-child is cancel second-child is submit thing. If you want to use the form without the modal you'll need to make a cancel button just so it can be hidden?

The submit button should work on its own, but I still think the cancel button should bubble some `"close"` or `"dismiss"` event that the modal will close on.

I keep thinking some extra element like `<mkt-event-wrap from="click" to="cancel"><button type="cancel">Cancel</button></mkt-event-wrap>` would make that easier but it is awfully verbose and quite different from how we've done things. There could be a specific `<mkt-prompt-dismiss><button type="cancel">Cancel</button></mkt-prompt-submit>`, possibly omitting the inner `<button>` from the markup.

Maybe the cancel button can have `type="cancel"` and the form's submit handler can catch that to dismiss the modal or dispatch the `"close"` event.