Cleanup capitalisation of applianceStatus

For consistency with other services like ngToast, and with the Angular
documentation.
Add "Help" link, to User Guide
Reword button text from "Install now" to "Install software update"

as per the Apple-style guidelines that say that a button should explain
the action clearly and not require additional context.
Cleanup: Use "===" instead of "==" in javascript

As per Crockford's advice ("==" does type coercion).