The Boston Symphony Orchestra has launched what it is calling an online conservatory on its web site, with features designed to draw in tech-savvy younger audiences, and make the old music the BSO plays relevant to a modern audience. So how did they do? Three tech experts give the orchestra high marks for the effort, but say the content and style have a long way to go. Still, the project may be the beginning of a new movement designed to drag symphony orchestras into the Internet era.