Fix log filename for Vagrant (#3053)

Actually, the log generated by debug mode is *.log
i.e. ubuntu-xenial-16.04-cloudimg-console.log

Global/Vagrant.gitignore

@@ -2,4 +2,4 @@
 .vagrant/
 
 # Log files (if you are creating logs in debug mode, uncomment this)
-# *.logs
+# *.log