qt: Periodic translations update

Update English translation from source code, and pull other translations
from Transifex.
Add sha2.cpp, with a native SHA256/SHA512 implementation.

This also moves the HMAC-SHA512 implementation there.
Switch script.cpp and hash.cpp to use sha2.cpp instead of OpenSSL.
Remove getwork() RPC call
Switch miner.cpp to use sha2 instead of OpenSSL.
Add SHA-1 implementation
Move crypto implementations to src/crypto/