r111783: Register extension for translatewiki.net.
Yes, I know, it is an example extension only. Added per request of Kaldari:
"Could someone add the HelloWorld MediaWiki extension into translatewiki?
It's an extension I made to assist in teaching people how to build MediaWiki extensions
I'm going to be using in a seminar I'm giving in Chile next month, so want it to be working in Spanish"