Don't translate SimpleDateFormat string.

The yyMMdd string that the sketch archiver tool uses to format archive
names was being localized (i.e. was wrapped in _()).  This gave an
error on startup (and the Arduino software would fail to launch), if
someone translated the string to something that wasn't a valid date
format.  Since this is an internal string, it shouldn't be translated.

http://code.google.com/p/arduino/issues/detail?id=942

app/src/processing/app/tools/Archiver.java

@@ -56,7 +56,7 @@ public void init(Editor editor) {
     numberFormat.setGroupingUsed(false); // no commas
     numberFormat.setMinimumIntegerDigits(digits);
 
-    dateFormat = new SimpleDateFormat(_("yyMMdd"));
+    dateFormat = new SimpleDateFormat("yyMMdd");
   }