New pbpack format support and crc calculator tool

In new SDK 2.0-BETA1 pbpack format was changed. Now it missing version string, and all remaining data are shifted.
Here is an updated version of unpackFirmware.py which supports both old and new formats (see also commit messages).
Also here is a simple tool which calculates STM32 CRC sum of a given file. It is useful e.g. when updating manifest.json in a patched firmware.

UPD: I also added a couple of new tools:
updateResources.py repacks firmware using new resource pack and updates all required checksums (supports both 1.x and 2.x);
prepareResourceProject.py uses SDK to repack firmware into pbpack (currently only supports 1.x SDK)