move generateQrCode() to static method in Utils

This makes it easy to use in multiple Activities.
only instantiate NsdHelper on Android versions that support NSD
local repo port, IP and IP String as app global

This stores globally variables for the IP address, port number, and
string version of the IP address. They can then be easily used elsewhere,
in other Activities, etc.
create wizard for bootstrapping with QR Code and wifi
slap Android's BluetoothChat example into Kerplapp
purge last remnants of "insecure" Bluetooth < 2.1 stuff
code clarity changes
support older than android-11