diff --git a/vendor/github.com/spf13/pflag/string.go b/vendor/github.com/spf13/pflag/string.go
new file mode 100644
index 0000000..04e0a26
--- /dev/null
+++ b/vendor/github.com/spf13/pflag/string.go
@@ -0,0 +1,80 @@
+package pflag
+
+// -- string Value
+type stringValue string
+
+func newStringValue(val string, p *string) *stringValue {
+	*p = val
+	return (*stringValue)(p)
+}
+
+func (s *stringValue) Set(val string) error {
+	*s = stringValue(val)
+	return nil
+}
+func (s *stringValue) Type() string {
+	return "string"
+}
+
+func (s *stringValue) String() string { return string(*s) }
+
+func stringConv(sval string) (interface{}, error) {
+	return sval, nil
+}
+
+// GetString return the string value of a flag with the given name
+func (f *FlagSet) GetString(name string) (string, error) {
+	val, err := f.getFlagType(name, "string", stringConv)
+	if err != nil {
+		return "", err
+	}
+	return val.(string), nil
+}
+
+// StringVar defines a string flag with specified name, default value, and usage string.
+// The argument p points to a string variable in which to store the value of the flag.
+func (f *FlagSet) StringVar(p *string, name string, value string, usage string) {
+	f.VarP(newStringValue(value, p), name, "", usage)
+}
+
+// StringVarP is like StringVar, but accepts a shorthand letter that can be used after a single dash.
+func (f *FlagSet) StringVarP(p *string, name, shorthand string, value string, usage string) {
+	f.VarP(newStringValue(value, p), name, shorthand, usage)
+}
+
+// StringVar defines a string flag with specified name, default value, and usage string.
+// The argument p points to a string variable in which to store the value of the flag.
+func StringVar(p *string, name string, value string, usage string) {
+	CommandLine.VarP(newStringValue(value, p), name, "", usage)
+}
+
+// StringVarP is like StringVar, but accepts a shorthand letter that can be used after a single dash.
+func StringVarP(p *string, name, shorthand string, value string, usage string) {
+	CommandLine.VarP(newStringValue(value, p), name, shorthand, usage)
+}
+
+// String defines a string flag with specified name, default value, and usage string.
+// The return value is the address of a string variable that stores the value of the flag.
+func (f *FlagSet) String(name string, value string, usage string) *string {
+	p := new(string)
+	f.StringVarP(p, name, "", value, usage)
+	return p
+}
+
+// StringP is like String, but accepts a shorthand letter that can be used after a single dash.
+func (f *FlagSet) StringP(name, shorthand string, value string, usage string) *string {
+	p := new(string)
+	f.StringVarP(p, name, shorthand, value, usage)
+	return p
+}
+
+// String defines a string flag with specified name, default value, and usage string.
+// The return value is the address of a string variable that stores the value of the flag.
+func String(name string, value string, usage string) *string {
+	return CommandLine.StringP(name, "", value, usage)
+}
+
+// StringP is like String, but accepts a shorthand letter that can be used after a single dash.
+func StringP(name, shorthand string, value string, usage string) *string {
+	return CommandLine.StringP(name, shorthand, value, usage)
+}