Keycard option greyed out for user on Android 8

[tschubotz]

Describe the bug See https://twitter.com/auryn_macmillan/status/1190279075304267777

Smartphone (please complete the following information):

• Device: BlackBerry KeyOne
• Android Version: Android 8.1.0
• App Version: 1.8.1

[tschubotz]

NFC was turned off.

We should let the user know in case their NFC is turned off. Added this to the list of improvement ideas: gnosis/safe#259