add beacon app, some Kconfig improvements. Repeated transmission reveals a transmission problem where the FIFO is filled but transmission does not start.

Add image

updater: blank check before erasing fw partition. Also fix nasty bug in bootloader spiflash waitwritecomplete().

Bootloader improvements: reset flash chip before leaving bootloader, global unlock it in case we are starting from a POR and not a reboot
Also add a progress indicator on the console.