add wizard for sending FDroid to another device via WiFi/QR
This is a little helper to direct people to get a new device to download
FDroid from another device that already has it. It first prompts them to
join the same wifi network, and offers a QR Code to associate to the same
wifi. The next step is a QR Code for getting the URL to the local repo.
The index.html on that local repo includes a download link for FDroid and
a repo link to the local repo.