Use os.EOL for line endings for text loggers (#590)

This change uses `os.EOL` for line endings instead of `\n`
This is useful for those of us using NodeJS on Windows where the easiest log reader is Notepad.exe
Fixes #589

lib/bunyan.js

@@ -908,7 +908,7 @@ Logger.prototype._emit = function (rec, noemit) {
     // Stringify the object (creates a warning str on error).
     var str;
     if (noemit || this.haveNonRawStreams) {
-        str = fastAndSafeJsonStringify(rec) + '\n';
+        str = fastAndSafeJsonStringify(rec) + os.EOL;
     }
 
     if (noemit)