This patch introduced serial bootloader functionality ported
from mynewt targets tree.
For achieving this following changes were applied:
- Modified boot_serial module for using, zephyr-os modules
(crc driver, mbedtls-base64 library) and the zephyr serial adapter module
introduced recently.
- Added service of boot serial recovery mode to main.
- Adapted the input parser to using static buffers.
Default serial-boot-pin configuration was added for nrf52_pca10040
and nrf52840_pca10056 boards.
Signed-off-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>