sha224 and sha256 cportable version implemented.
Moved sha224 instance to its own module at Raaz.Hash.Sha224.Instance
sha384 and sha512 cportable version implemented.
Moved sha384 instance to its own module at Raaz.Hash.Sha384.Instance
Tests fixup for sha224 and sha384 instances moved to their own module.
Fixing tests for
* Moving sha224 instance from Raaz.Hash.Sha256.Instance to Raaz.Hash.Sha224.Instance
* Moving sha384 instance from Raaz.Hash.Sha512.Instance to Raaz.Hash.Sha384.Instance
Cleaned up undefs in cportables.
Optimized one bit operation in MAJ function of sha hashes