Localization testing page should show English, too

Created by: amire80

The localization testing page at http://devel.mathjax.org/testing/mathjax/MathJax-issue530/test/localization.html?locale=de doesn't allow to choose English from the dropdown menu at the top. This should be possible. It will make bug reporting easier - the testers will be able to cite the English messages that all the developers will understand.