Added Paddable Gadget for Blake compatibility
Hash fixup for Paddable Gadget
raaz-random bug fixup
Merge changes to facilitate blake like hashes

The previous interface for gadget was not sufficent to capture the
final block of compression of a HAIFA hash like blake. While the
length hashed so far can be kept inside the Memory element of the
gadget, the previous implementation did not provide a way to pass
the actual size to the final stage of hashing.