Update vendoring via vndr

gateway/vendor/github.com/Azure/go-ansiterm/utilities.go

@@ -0,0 +1,21 @@
+package ansiterm
+
+import (
+	"strconv"
+)
+
+func sliceContains(bytes []byte, b byte) bool {
+	for _, v := range bytes {
+		if v == b {
+			return true
+		}
+	}
+
+	return false
+}
+
+func convertBytesToInteger(bytes []byte) int {
+	s := string(bytes)
+	i, _ := strconv.Atoi(s)
+	return i
+}