func NewRequestValidator(authToken string) RequestValidator {
	return RequestValidator{
		signingKey: []byte(authToken),
	}
}
NewRequestValidator returns a new RequestValidator which uses the specified auth token when verifying
Twilio signatures.
package client
import (
	"crypto/hmac"
	"crypto/sha1"
	"crypto/sha256"
	"crypto/subtle"
	"encoding/base64"
	"fmt"
	urllib "net/url"
	"sort"
	"strings"
)
type RequestValidator struct {
	signingKey []byte
}