manifest: mcuboot update

- Added precise check of the image size.
- loader: Added post copy hook to swap function.
- Added Kconfig option for setting swap using move as the default
  swap algorithm.
- zephyr: fixed ram loading for ARM, with correct handling of
  the vector table when code has moved to RAM.

- imgtool: Added option to export public PEM.

Signed-off-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>