Bug 847168 - [User Story] Email Signature

I believe this should be a pack-switch and not a pack-checkbox. For things that can be turned on and off, the switch is better. We only use a checkbox for the "Set as default" because it can only be toggled one way, to on.

Also, the styling around the signature string indicates it is a select element. However, it navigates to a new card, so we should use the button with > chevron style. You can see an example in the Settings, Developer card, the "Developer Hud" entry.

It should mean just switching the element to a button and using the class="icon icon-view" on it.

Once we have that all sorted, you should take some screenshots, then attach them to the bug, so we can get UX review. I would show each screen that is affected by the pull request. If you have an image editor, I normally use that to stitch all the screenshots into a horizontal row, so that UX just has to look at one image.

Attach that image as an attachment to the bug, then ask for ui-review r? from :peko. We will want UX r+ before landing.

But feel free to ping me for a final review of the UI once you address this feedback before asking UX. We can make sure we have all the code settled, along with any HTML/CSS, before bothering them.