vendor: Replace Sirupsen/logrus with sirupsen/logrus

With:

  $ git mv vendor/github.com/{S,s}irupsen
  $ sed -i 's/Sirupsen/sirupsen/g' $(git grep -l Sirupsen)

catching up with the upstream lowercasing [1,2,3,4].  Because of the
compatibility issues discussed in [3], some consumers may prefer to
use the old uppercase version until they have time to update their
other Logrus consumers to the new lowercase form.

[1]: https://github.com/sirupsen/logrus/blame/v1.0.3/README.md#L6
[2]: https://github.com/sirupsen/logrus/pull/384
[3]: https://github.com/sirupsen/logrus/issues/570#issuecomment-313933276
[4]: https://github.com/sirupsen/logrus/issues/553

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

@@ -0,0 +1,62 @@
+package logrus
+
+import (
+	"bufio"
+	"io"
+	"runtime"
+)
+
+func (logger *Logger) Writer() *io.PipeWriter {
+	return logger.WriterLevel(InfoLevel)
+}
+
+func (logger *Logger) WriterLevel(level Level) *io.PipeWriter {
+	return NewEntry(logger).WriterLevel(level)
+}
+
+func (entry *Entry) Writer() *io.PipeWriter {
+	return entry.WriterLevel(InfoLevel)
+}
+
+func (entry *Entry) WriterLevel(level Level) *io.PipeWriter {
+	reader, writer := io.Pipe()
+
+	var printFunc func(args ...interface{})
+
+	switch level {
+	case DebugLevel:
+		printFunc = entry.Debug
+	case InfoLevel:
+		printFunc = entry.Info
+	case WarnLevel:
+		printFunc = entry.Warn
+	case ErrorLevel:
+		printFunc = entry.Error
+	case FatalLevel:
+		printFunc = entry.Fatal
+	case PanicLevel:
+		printFunc = entry.Panic
+	default:
+		printFunc = entry.Print
+	}
+
+	go entry.writerScanner(reader, printFunc)
+	runtime.SetFinalizer(writer, writerFinalizer)
+
+	return writer
+}
+
+func (entry *Entry) writerScanner(reader *io.PipeReader, printFunc func(args ...interface{})) {
+	scanner := bufio.NewScanner(reader)
+	for scanner.Scan() {
+		printFunc(scanner.Text())
+	}
+	if err := scanner.Err(); err != nil {
+		entry.Errorf("Error while reading from Writer: %s", err)
+	}
+	reader.Close()
+}
+
+func writerFinalizer(writer *io.PipeWriter) {
+	writer.Close()
+}