standalone mode for iOS

[JdenHartog]

Fixes #[none] .

Changes proposed in this pull request:

• This will make the admin page look more like a native iOS application when started from Home Screen on iOS. It also won't create a tab in iOS Safari and saves spacetime. See Hiding Safari User Interface Components on:
  https://developer.apple.com/library/content/documentation/AppleApplications/Reference/SafariWebContent/ConfiguringWebApplications/ConfiguringWebApplications.html

@pi-hole/dashboard

[CLAassistant]

All committers have signed the CLA.

[DL6ER]

I like the idea, however, I cannot test it (because of not having an iOS device). Could you provide screenshots before/after?

[PromoFaux]

Do you have an android device @DL6ER? I think this is essentially the same as using the "add to home screen" option on Chrome... I might be wrong.

[PromoFaux]

OK, to revise my above comment...

Using "Add to homescreen" on Chrome without this will just open it as a new tab. With this modification, it opens as it's own "app". Nice little detail.

Approved

[DL6ER]

Just tested it, Chrome even shows a splash screen on startup. Very nice!

[AzureMarker]

Approved.

[PromoFaux]

@JdenHartog In order for us to merge this pull request, we need you to sign the contributor license agreement

Thanks!

[JdenHartog]

You're welcome! Thank you guys for pi-hole!

I signed the contributor license agreement.