move ethutil helper crypto functions to ethcrypto/crypto

ethcrypto/crypto.go

+package ethcrypto
+
+import (
+	"code.google.com/p/go.crypto/ripemd160"
+	"crypto/sha256"
+	"github.com/obscuren/sha3"
+)
+
+func Sha256Bin(data []byte) []byte {
+	hash := sha256.Sum256(data)
+
+	return hash[:]
+}
+
+func Ripemd160(data []byte) []byte {
+	ripemd := ripemd160.New()
+	ripemd.Write(data)
+
+	return ripemd.Sum(nil)
+}
+
+func Sha3Bin(data []byte) []byte {
+	d := sha3.NewKeccak256()
+	d.Write(data)
+
+	return d.Sum(nil)
+}