Set a minimum spin time of 1 second for gh-spin-button
Set a minimum spin time of 1 second for gh-spin-button

refs #5652, #5719
- adds a timeout to `gh-spin-button` so the spinner is always shown for at least 1 second

As a stopgap solution before #5719 can be implemented it was decided to keep the button spinning for a minimum time, even if the associated action completes quickly. Discussion can be found at https://ghost.slack.com/archives/dev/p1440670418004358

TryGhost/Ghost,TryGhost/Ghost,TryGhost/Ghost