Firefox OS is now going to happen. When it was announced a year ago, the carriers said they were in. Now they’re about to prove it: this summer, Telefonica will roll out handsets in Spain, Brazil, Venezuela and Colombia, and Deutsche Telekom and Telenor will do the same in Europe.But will it succeed? To figure that out, we need to look at a number of variables, including the OS itself, but mainly what it represents for those all-important carriers.From an open standards perspective, the Firefox OS is as pure as it gets right now. The whole thing is based on HTML5 – it’s all about escaping Google and Apple’s walled gardens and frolicking freely