Mainline dedicated hardware kiosk changes - 2nd Edition

[pc-coholic]

This superseeds #160 in an attempt to make the rebase easier.

ToDo:

• String for "Time after gate open"
• Make NFC work again
• BaseScanActivity: NFC showLoadingCard()
• BaseScanActivity/MainScanActivity: LED in Base?
• GateUtils Exception("error_print_no_app") will crash the whole app when IO-Service is not installed
• Check new TR51-build if isTR51() is correct before merge.
• Check Auto-Camera/Scanner Mode for kt0345/TR51-detection

Also merge:

• Support for CheckResult.locale and check(useOrderLocale) libpretixsync#54

After merge:

• integrate https://github.com/pretix/pretixscan-android/tree/kiosk-a11y, only commit: cb5b6e3

[pc-coholic]

Tested in-office with kt0345 turnstile and confirmed working.