htpasswd: refactor and add Passwd methods

Signed-off-by: Nagy Károly Gábriel <k@jpi.io>

 	if err != nil {
 		return err
 	}
+	newpp, err := pp.CreateUser(user, passwd, algo)

+}
+
+// Byte will return the Passwd as a byte slice
+func (pp Passwds) Byte() []byte {

 	return fmt.Errorf("unsupported hash algorithm %v", alg)
 }
 
+func identifyHash(h string) (HashAlgorithm, error) {

 	return apr1_crypt.New().Verify(hashedPassword, []byte(password))
 }
 
+func hashBcrypt(passwd string) (string, error) {

 	return nil
 }
 
+func hashSha512(passwd string) (string, error) {

+func (pp Passwds) CreateUser(user, passwd string, algo HashAlgorithm) (Passwds, error) {
 	if _, exists := pp[user]; exists {
-		return fmt.Errorf("user %s already exists", user)
+		return nil, fmt.Errorf("user %s already exists", user)