diff --git a/vendor/github.com/json-iterator/go/stream_str.go b/vendor/github.com/json-iterator/go/stream_str.go
new file mode 100644
index 0000000..54c2ba0
--- /dev/null
+++ b/vendor/github.com/json-iterator/go/stream_str.go
@@ -0,0 +1,372 @@
+package jsoniter
+
+import (
+	"unicode/utf8"
+)
+
+// htmlSafeSet holds the value true if the ASCII character with the given
+// array position can be safely represented inside a JSON string, embedded
+// inside of HTML <script> tags, without any additional escaping.
+//
+// All values are true except for the ASCII control characters (0-31), the
+// double quote ("), the backslash character ("\"), HTML opening and closing
+// tags ("<" and ">"), and the ampersand ("&").
+var htmlSafeSet = [utf8.RuneSelf]bool{
+	' ':      true,
+	'!':      true,
+	'"':      false,
+	'#':      true,
+	'$':      true,
+	'%':      true,
+	'&':      false,
+	'\'':     true,
+	'(':      true,
+	')':      true,
+	'*':      true,
+	'+':      true,
+	',':      true,
+	'-':      true,
+	'.':      true,
+	'/':      true,
+	'0':      true,
+	'1':      true,
+	'2':      true,
+	'3':      true,
+	'4':      true,
+	'5':      true,
+	'6':      true,
+	'7':      true,
+	'8':      true,
+	'9':      true,
+	':':      true,
+	';':      true,
+	'<':      false,
+	'=':      true,
+	'>':      false,
+	'?':      true,
+	'@':      true,
+	'A':      true,
+	'B':      true,
+	'C':      true,
+	'D':      true,
+	'E':      true,
+	'F':      true,
+	'G':      true,
+	'H':      true,
+	'I':      true,
+	'J':      true,
+	'K':      true,
+	'L':      true,
+	'M':      true,
+	'N':      true,
+	'O':      true,
+	'P':      true,
+	'Q':      true,
+	'R':      true,
+	'S':      true,
+	'T':      true,
+	'U':      true,
+	'V':      true,
+	'W':      true,
+	'X':      true,
+	'Y':      true,
+	'Z':      true,
+	'[':      true,
+	'\\':     false,
+	']':      true,
+	'^':      true,
+	'_':      true,
+	'`':      true,
+	'a':      true,
+	'b':      true,
+	'c':      true,
+	'd':      true,
+	'e':      true,
+	'f':      true,
+	'g':      true,
+	'h':      true,
+	'i':      true,
+	'j':      true,
+	'k':      true,
+	'l':      true,
+	'm':      true,
+	'n':      true,
+	'o':      true,
+	'p':      true,
+	'q':      true,
+	'r':      true,
+	's':      true,
+	't':      true,
+	'u':      true,
+	'v':      true,
+	'w':      true,
+	'x':      true,
+	'y':      true,
+	'z':      true,
+	'{':      true,
+	'|':      true,
+	'}':      true,
+	'~':      true,
+	'\u007f': true,
+}
+
+// safeSet holds the value true if the ASCII character with the given array
+// position can be represented inside a JSON string without any further
+// escaping.
+//
+// All values are true except for the ASCII control characters (0-31), the
+// double quote ("), and the backslash character ("\").
+var safeSet = [utf8.RuneSelf]bool{
+	' ':      true,
+	'!':      true,
+	'"':      false,
+	'#':      true,
+	'$':      true,
+	'%':      true,
+	'&':      true,
+	'\'':     true,
+	'(':      true,
+	')':      true,
+	'*':      true,
+	'+':      true,
+	',':      true,
+	'-':      true,
+	'.':      true,
+	'/':      true,
+	'0':      true,
+	'1':      true,
+	'2':      true,
+	'3':      true,
+	'4':      true,
+	'5':      true,
+	'6':      true,
+	'7':      true,
+	'8':      true,
+	'9':      true,
+	':':      true,
+	';':      true,
+	'<':      true,
+	'=':      true,
+	'>':      true,
+	'?':      true,
+	'@':      true,
+	'A':      true,
+	'B':      true,
+	'C':      true,
+	'D':      true,
+	'E':      true,
+	'F':      true,
+	'G':      true,
+	'H':      true,
+	'I':      true,
+	'J':      true,
+	'K':      true,
+	'L':      true,
+	'M':      true,
+	'N':      true,
+	'O':      true,
+	'P':      true,
+	'Q':      true,
+	'R':      true,
+	'S':      true,
+	'T':      true,
+	'U':      true,
+	'V':      true,
+	'W':      true,
+	'X':      true,
+	'Y':      true,
+	'Z':      true,
+	'[':      true,
+	'\\':     false,
+	']':      true,
+	'^':      true,
+	'_':      true,
+	'`':      true,
+	'a':      true,
+	'b':      true,
+	'c':      true,
+	'd':      true,
+	'e':      true,
+	'f':      true,
+	'g':      true,
+	'h':      true,
+	'i':      true,
+	'j':      true,
+	'k':      true,
+	'l':      true,
+	'm':      true,
+	'n':      true,
+	'o':      true,
+	'p':      true,
+	'q':      true,
+	'r':      true,
+	's':      true,
+	't':      true,
+	'u':      true,
+	'v':      true,
+	'w':      true,
+	'x':      true,
+	'y':      true,
+	'z':      true,
+	'{':      true,
+	'|':      true,
+	'}':      true,
+	'~':      true,
+	'\u007f': true,
+}
+
+var hex = "0123456789abcdef"
+
+// WriteStringWithHTMLEscaped write string to stream with html special characters escaped
+func (stream *Stream) WriteStringWithHTMLEscaped(s string) {
+	valLen := len(s)
+	stream.buf = append(stream.buf, '"')
+	// write string, the fast path, without utf8 and escape support
+	i := 0
+	for ; i < valLen; i++ {
+		c := s[i]
+		if c < utf8.RuneSelf && htmlSafeSet[c] {
+			stream.buf = append(stream.buf, c)
+		} else {
+			break
+		}
+	}
+	if i == valLen {
+		stream.buf = append(stream.buf, '"')
+		return
+	}
+	writeStringSlowPathWithHTMLEscaped(stream, i, s, valLen)
+}
+
+func writeStringSlowPathWithHTMLEscaped(stream *Stream, i int, s string, valLen int) {
+	start := i
+	// for the remaining parts, we process them char by char
+	for i < valLen {
+		if b := s[i]; b < utf8.RuneSelf {
+			if htmlSafeSet[b] {
+				i++
+				continue
+			}
+			if start < i {
+				stream.WriteRaw(s[start:i])
+			}
+			switch b {
+			case '\\', '"':
+				stream.writeTwoBytes('\\', b)
+			case '\n':
+				stream.writeTwoBytes('\\', 'n')
+			case '\r':
+				stream.writeTwoBytes('\\', 'r')
+			case '\t':
+				stream.writeTwoBytes('\\', 't')
+			default:
+				// This encodes bytes < 0x20 except for \t, \n and \r.
+				// If escapeHTML is set, it also escapes <, >, and &
+				// because they can lead to security holes when
+				// user-controlled strings are rendered into JSON
+				// and served to some browsers.
+				stream.WriteRaw(`\u00`)
+				stream.writeTwoBytes(hex[b>>4], hex[b&0xF])
+			}
+			i++
+			start = i
+			continue
+		}
+		c, size := utf8.DecodeRuneInString(s[i:])
+		if c == utf8.RuneError && size == 1 {
+			if start < i {
+				stream.WriteRaw(s[start:i])
+			}
+			stream.WriteRaw(`\ufffd`)
+			i++
+			start = i
+			continue
+		}
+		// U+2028 is LINE SEPARATOR.
+		// U+2029 is PARAGRAPH SEPARATOR.
+		// They are both technically valid characters in JSON strings,
+		// but don't work in JSONP, which has to be evaluated as JavaScript,
+		// and can lead to security holes there. It is valid JSON to
+		// escape them, so we do so unconditionally.
+		// See http://timelessrepo.com/json-isnt-a-javascript-subset for discussion.
+		if c == '\u2028' || c == '\u2029' {
+			if start < i {
+				stream.WriteRaw(s[start:i])
+			}
+			stream.WriteRaw(`\u202`)
+			stream.writeByte(hex[c&0xF])
+			i += size
+			start = i
+			continue
+		}
+		i += size
+	}
+	if start < len(s) {
+		stream.WriteRaw(s[start:])
+	}
+	stream.writeByte('"')
+}
+
+// WriteString write string to stream without html escape
+func (stream *Stream) WriteString(s string) {
+	valLen := len(s)
+	stream.buf = append(stream.buf, '"')
+	// write string, the fast path, without utf8 and escape support
+	i := 0
+	for ; i < valLen; i++ {
+		c := s[i]
+		if c > 31 && c != '"' && c != '\\' {
+			stream.buf = append(stream.buf, c)
+		} else {
+			break
+		}
+	}
+	if i == valLen {
+		stream.buf = append(stream.buf, '"')
+		return
+	}
+	writeStringSlowPath(stream, i, s, valLen)
+}
+
+func writeStringSlowPath(stream *Stream, i int, s string, valLen int) {
+	start := i
+	// for the remaining parts, we process them char by char
+	for i < valLen {
+		if b := s[i]; b < utf8.RuneSelf {
+			if safeSet[b] {
+				i++
+				continue
+			}
+			if start < i {
+				stream.WriteRaw(s[start:i])
+			}
+			switch b {
+			case '\\', '"':
+				stream.writeTwoBytes('\\', b)
+			case '\n':
+				stream.writeTwoBytes('\\', 'n')
+			case '\r':
+				stream.writeTwoBytes('\\', 'r')
+			case '\t':
+				stream.writeTwoBytes('\\', 't')
+			default:
+				// This encodes bytes < 0x20 except for \t, \n and \r.
+				// If escapeHTML is set, it also escapes <, >, and &
+				// because they can lead to security holes when
+				// user-controlled strings are rendered into JSON
+				// and served to some browsers.
+				stream.WriteRaw(`\u00`)
+				stream.writeTwoBytes(hex[b>>4], hex[b&0xF])
+			}
+			i++
+			start = i
+			continue
+		}
+		i++
+		continue
+	}
+	if start < len(s) {
+		stream.WriteRaw(s[start:])
+	}
+	stream.writeByte('"')
+}