By Mia Shanley STOCKHOLM (Reuters) – A Nordic venture capital firm says it has built the worlds largest database of businesses dealing in Bitcoins in an effort to shed light on a virtual currency which has seen its value rocket in the past year. Creandum said the database contained more than 300 companies trading Bitcoins – ranging from exchanges to payment processors and gambling companies – and was intended to give entrepreneurs and investors an overview of companies with a significant role in the Bitcoin system.