Add compatibility with 8devices NUY

[mantas-p]

Hi,

This is part of integration of NUY hardware support to Arduino Yun repositories.
This PR adds:

• NUY platform support
• Build target 'Yun_compat' for building Yun and NUY images with compatible kernel modules
• Add BOSSA to default config
• Patch to busybox init, that allows use of /dev/ttyATH0 for programming Arduino with serial bootloader

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