Added the new Google Plus vanity URL

Might be a nice first test case for https://github.com/OpenRA/OpenRAWeb/pull/135.
No, while the link seems case-insensitive https://plus.google.com/+OpenRAnet it will redirect to the DomainTopleveldomain camel casing. A similiar annoying behavior as http://www.moddb.com/games/openra sadly. There is a reason no one likes and uses G+...