diff --git a/vendor/github.com/spf13/pflag/string_slice.go b/vendor/github.com/spf13/pflag/string_slice.go
new file mode 100644
index 0000000..0cd3ccc
--- /dev/null
+++ b/vendor/github.com/spf13/pflag/string_slice.go
@@ -0,0 +1,149 @@
+package pflag
+
+import (
+	"bytes"
+	"encoding/csv"
+	"strings"
+)
+
+// -- stringSlice Value
+type stringSliceValue struct {
+	value   *[]string
+	changed bool
+}
+
+func newStringSliceValue(val []string, p *[]string) *stringSliceValue {
+	ssv := new(stringSliceValue)
+	ssv.value = p
+	*ssv.value = val
+	return ssv
+}
+
+func readAsCSV(val string) ([]string, error) {
+	if val == "" {
+		return []string{}, nil
+	}
+	stringReader := strings.NewReader(val)
+	csvReader := csv.NewReader(stringReader)
+	return csvReader.Read()
+}
+
+func writeAsCSV(vals []string) (string, error) {
+	b := &bytes.Buffer{}
+	w := csv.NewWriter(b)
+	err := w.Write(vals)
+	if err != nil {
+		return "", err
+	}
+	w.Flush()
+	return strings.TrimSuffix(b.String(), "\n"), nil
+}
+
+func (s *stringSliceValue) Set(val string) error {
+	v, err := readAsCSV(val)
+	if err != nil {
+		return err
+	}
+	if !s.changed {
+		*s.value = v
+	} else {
+		*s.value = append(*s.value, v...)
+	}
+	s.changed = true
+	return nil
+}
+
+func (s *stringSliceValue) Type() string {
+	return "stringSlice"
+}
+
+func (s *stringSliceValue) String() string {
+	str, _ := writeAsCSV(*s.value)
+	return "[" + str + "]"
+}
+
+func stringSliceConv(sval string) (interface{}, error) {
+	sval = sval[1 : len(sval)-1]
+	// An empty string would cause a slice with one (empty) string
+	if len(sval) == 0 {
+		return []string{}, nil
+	}
+	return readAsCSV(sval)
+}
+
+// GetStringSlice return the []string value of a flag with the given name
+func (f *FlagSet) GetStringSlice(name string) ([]string, error) {
+	val, err := f.getFlagType(name, "stringSlice", stringSliceConv)
+	if err != nil {
+		return []string{}, err
+	}
+	return val.([]string), nil
+}
+
+// StringSliceVar 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.
+// Compared to StringArray flags, StringSlice flags take comma-separated value as arguments and split them accordingly.
+// For example:
+//   --ss="v1,v2" -ss="v3"
+// will result in
+//   []string{"v1", "v2", "v3"}
+func (f *FlagSet) StringSliceVar(p *[]string, name string, value []string, usage string) {
+	f.VarP(newStringSliceValue(value, p), name, "", usage)
+}
+
+// StringSliceVarP is like StringSliceVar, but accepts a shorthand letter that can be used after a single dash.
+func (f *FlagSet) StringSliceVarP(p *[]string, name, shorthand string, value []string, usage string) {
+	f.VarP(newStringSliceValue(value, p), name, shorthand, usage)
+}
+
+// StringSliceVar 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.
+// Compared to StringArray flags, StringSlice flags take comma-separated value as arguments and split them accordingly.
+// For example:
+//   --ss="v1,v2" -ss="v3"
+// will result in
+//   []string{"v1", "v2", "v3"}
+func StringSliceVar(p *[]string, name string, value []string, usage string) {
+	CommandLine.VarP(newStringSliceValue(value, p), name, "", usage)
+}
+
+// StringSliceVarP is like StringSliceVar, but accepts a shorthand letter that can be used after a single dash.
+func StringSliceVarP(p *[]string, name, shorthand string, value []string, usage string) {
+	CommandLine.VarP(newStringSliceValue(value, p), name, shorthand, usage)
+}
+
+// StringSlice 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.
+// Compared to StringArray flags, StringSlice flags take comma-separated value as arguments and split them accordingly.
+// For example:
+//   --ss="v1,v2" -ss="v3"
+// will result in
+//   []string{"v1", "v2", "v3"}
+func (f *FlagSet) StringSlice(name string, value []string, usage string) *[]string {
+	p := []string{}
+	f.StringSliceVarP(&p, name, "", value, usage)
+	return &p
+}
+
+// StringSliceP is like StringSlice, but accepts a shorthand letter that can be used after a single dash.
+func (f *FlagSet) StringSliceP(name, shorthand string, value []string, usage string) *[]string {
+	p := []string{}
+	f.StringSliceVarP(&p, name, shorthand, value, usage)
+	return &p
+}
+
+// StringSlice 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.
+// Compared to StringArray flags, StringSlice flags take comma-separated value as arguments and split them accordingly.
+// For example:
+//   --ss="v1,v2" -ss="v3"
+// will result in
+//   []string{"v1", "v2", "v3"}
+func StringSlice(name string, value []string, usage string) *[]string {
+	return CommandLine.StringSliceP(name, "", value, usage)
+}
+
+// StringSliceP is like StringSlice, but accepts a shorthand letter that can be used after a single dash.
+func StringSliceP(name, shorthand string, value []string, usage string) *[]string {
+	return CommandLine.StringSliceP(name, shorthand, value, usage)
+}