vendor: update sources

```shell
dep ensure -update
```

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

vendor/github.com/sirupsen/logrus/json_formatter.go

@@ -1,6 +1,7 @@
 package logrus
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 )
@@ -10,13 +11,6 @@ type fieldKey string
 // FieldMap allows customization of the key names for default fields.
 type FieldMap map[fieldKey]string
 
-// Default key names for the default fields
-const (
-	FieldKeyMsg   = "msg"
-	FieldKeyLevel = "level"
-	FieldKeyTime  = "time"
-)
-
 func (f FieldMap) resolve(key fieldKey) string {
 	if k, ok := f[key]; ok {
 		return k
@@ -40,17 +34,21 @@ type JSONFormatter struct {
 	// As an example:
 	// formatter := &JSONFormatter{
 	//   	FieldMap: FieldMap{
-	// 		 FieldKeyTime: "@timestamp",
+	// 		 FieldKeyTime:  "@timestamp",
 	// 		 FieldKeyLevel: "@level",
-	// 		 FieldKeyMsg: "@message",
+	// 		 FieldKeyMsg:   "@message",
+	// 		 FieldKeyFunc:  "@caller",
 	//    },
 	// }
 	FieldMap FieldMap
+
+	// PrettyPrint will indent all json logs
+	PrettyPrint bool
 }
 
 // Format renders a single log entry
 func (f *JSONFormatter) Format(entry *Entry) ([]byte, error) {
-	data := make(Fields, len(entry.Data)+3)
+	data := make(Fields, len(entry.Data)+4)
 	for k, v := range entry.Data {
 		switch v := v.(type) {
 		case error:
@@ -68,22 +66,40 @@ func (f *JSONFormatter) Format(entry *Entry) ([]byte, error) {
 		data = newData
 	}
 
-	prefixFieldClashes(data, f.FieldMap)
+	prefixFieldClashes(data, f.FieldMap, entry.HasCaller())
 
 	timestampFormat := f.TimestampFormat
 	if timestampFormat == "" {
 		timestampFormat = defaultTimestampFormat
 	}
 
+	if entry.err != "" {
+		data[f.FieldMap.resolve(FieldKeyLogrusError)] = entry.err
+	}
 	if !f.DisableTimestamp {
 		data[f.FieldMap.resolve(FieldKeyTime)] = entry.Time.Format(timestampFormat)
 	}
 	data[f.FieldMap.resolve(FieldKeyMsg)] = entry.Message
 	data[f.FieldMap.resolve(FieldKeyLevel)] = entry.Level.String()
+	if entry.HasCaller() {
+		data[f.FieldMap.resolve(FieldKeyFunc)] = entry.Caller.Function
+		data[f.FieldMap.resolve(FieldKeyFile)] = fmt.Sprintf("%s:%d", entry.Caller.File, entry.Caller.Line)
+	}
 
-	serialized, err := json.Marshal(data)
-	if err != nil {
+	var b *bytes.Buffer
+	if entry.Buffer != nil {
+		b = entry.Buffer
+	} else {
+		b = &bytes.Buffer{}
+	}
+
+	encoder := json.NewEncoder(b)
+	if f.PrettyPrint {
+		encoder.SetIndent("", "  ")
+	}
+	if err := encoder.Encode(data); err != nil {
 		return nil, fmt.Errorf("Failed to marshal fields to JSON, %v", err)
 	}
-	return append(serialized, '\n'), nil
+
+	return b.Bytes(), nil
 }