LONDON (Reuters) -WikiLeaks founder Julian Assange married his long-term partner Stella Moris inside a British high-security prison on Wednesday at a small ceremony attended by just four guests, two official witnesses and two guards. Assange is being held in jail while U.S. authorities seek his extradition to face trial on 18 counts relating to WikiLeaks’ release of vast troves of confidential U.S. military records and diplomatic cables more than a decade ago. “I am very happy and very sad. I love Julian with all my heart, and I wish he were here,” Moris said outside the gates of Belmarsh pris…