[youtube]http://www.youtube.com/watch?v=zfScv0dJp3Y[/youtube] It’s the time of year for caroling and season’s greetings emanating from the hearth of the Navy’s top officer’s house. “Hello, shipmates. It’s been a challenging year but it’s been a great year, and Darleen and I want to thank you for all that you do,” said Chief of Naval Operations Adm. Jon Greenert in his third holiday video, posted online Wednesday —  a possible to reference to the variety of crises Greenert confronted in 2013, from extended deployments to budget woes to a minesweeper shipwreck. Greenert, along with his wife, Darleen, sounded a warm tone to the backdrop…