By Peter Apps and Henning Gloystein LONDON (Reuters) - As it tries to play Russia off against Europe to salvage its economy, Cyprus has embarked on a high-stakes poker game that could see almost everyone lose. Its banks shattered by exposure to Greek debt, the island state urgently needs a way of bailing out its financial system. Cypriot policymakers hope they can begin to monetise as yet undeveloped offshore gas fields and position themselves as a vital source of energy for Europe. ...