Merge pull request #481 from darrenmcc/import-io

Fixed import

terminal_appengine.go

@@ -2,6 +2,8 @@
 
 package logrus
 
+import "io"
+
 // IsTerminal returns true if stderr's file descriptor is a terminal.
 func IsTerminal(f io.Writer) bool {
 	return true

terminal_solaris.go

@@ -3,6 +3,7 @@
 package logrus
 
 import (
+	"io"
 	"os"
 
 	"golang.org/x/sys/unix"

terminal_windows.go

@@ -8,8 +8,8 @@
 package logrus
 
 import (
-	"io"	
-	"os"	
+	"io"
+	"os"
 	"syscall"
 	"unsafe"
 )