Bitcoin is the world's biggest cryptocurrency and its value remains well in front of the likes of Ripple, Litecoin, Peercoin - and most recently, Dogecoin. But 2014 has been a tough year for the online currency and people are beginning to question how much longer it can survive. We take a look at some of the recent revelations to rock the world of Bitcoin and ask you to consider whether it could be on the way out...